US History

How was the United States created, and how did it become a world power? Although the US is a relatively young country, it has a complex history characterized by vast periods of transformation. How did American ideals, traditions, and society form? And what does it mean to be a world power anyway?

US History US History

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Table of contents

    US history periods timeline

    Prehistory - 1492Columbian America
    1585 - 1763Colonial America
    1763 - 1783The American Revolution
    1783 - 1803The New Nation of America
    1803 - 1861American Expansionism
    1861 - 1865The American Civil War
    1865 - 1877The Reconstruction Era
    1877 - 1900The American Gilded Age
    1897 - 1920The Progressive Era
    1920 - 1929The Roaring Twenties
    1929 - 1941The Great Depression
    1919 - 1941Interwar Foreign Policy
    1939 - 1945The US in World War II
    1945-1991The US in the Cold War

    Columbian America

    Before Europeans arrived in 1492, numerous Indigenous societies prospered. In Central and South America, the Aztecs controlled most of present-day Mexico and boasted the most populous city, Tenochtitlan.

    US History  Tenochtitlan Illustration StudySmarterFig. 1

    Tenochtitlan Illustration

    Many Indigenous societies inhabited the North American continent, including the arctic experts of the Inuit, the Iroquois and Algonquin in the woodland east, the Cherokee in the southeast, and the Navajo in the southwest, to name a few.

    The rediscovery of the “New World” by Christopher Columbus in 1492 changed the Indigenous world and the Old World forever. Motivated by a desire for natural resources such as gold, silver, and copper, Europe developed rapid and competitive colonization. Within a century, Spain and Portugal controlled most of the known New World and reaped the economic benefits.

    Old and New World

    The Old World describes Europe and its neighbors, Asia and Africa. It was used to distinguish between the 'new world' or the lands discovered across the Atlantic: the Americas.


    The process of establishing control over an area and its people

    The Columbian Exchange was the transfer of new flora, fauna, ideas, and technologies between the Old and New World. Not all of these exchanges were positive. European diseases such as smallpox eradicated close to ninety percent of the Indigenous populations of North and South America. Disease paved the way for a conquest of the continents with relative ease.

    Colonial America

    Following the Spanish and Portuguese example, France and the Netherlands started to explore North America. The French claimed territory around the Great Lakes and the Saint Lawrence River, and the Dutch established New Netherland in present-day New York. Both nations profited from the fur trade with Indigenous Peoples.

    US History The Lost Colony StudySmarterFig. 2 The Lost Colony

    The English began their explorations in the 1580s, but their initial attempts failed, such as with the Lost Colony of Roanoke. The first thriving colony was Jamestown, established in 1607 in Virginia. The British eventually ruled over thirteen colonies, which would come to make up the original United States.

    • The New England Colonies had significant Puritan influence. The Puritans were radical Protestants persecuted in England for criticizing the monarchy and the church.
    • The Middle Colonies of Pennsylvania, New York, New Jersey, and Delaware offered religious toleration and found economic success in wheat, grain, and mercantile industries. They benefited from the trade network across the Atlantic Ocean, which aided the use and expansion of African slave labor.
    • Southern colonies relied on plantation farming to sustain them, and soon African slave labor was used to work these farms.

    US History British Colonies StudySmarterFig. 3 British Colonies

    US history: summary of the American Revolution

    The American Revolution lasted eight years and resulted in independence from the British.

    Below is a timeline of the major events.

    1763 - 1773

    Protests and boycotts spread throughout the colonies as Parliament passed these acts with little American representation. Conflicts erupted between colonists and British troops.

    1770The Boston Massacre
    1773The Boston Tea Party
    1774The Intolerable ActsThe First Continental Congress
    1775The Battle of Lexington and ConcordThe Second Continental Congress
    1775 - 1783The American War of Independence
    1776Ratification of the Declaration of Independence - this created the United States
    1783The Treaty of Paris - end of the conflict

    US History Declaration of Independence 1819 StudySmarterFig. 4 Declaration of Independance

    The new nation of America

    After the creation of the United States, Congress ratified the Articles of Confederation, which created a purposefully weak central government designed to give the individual states of America more sovereignty.

    However, the Articles of Confederation failed to provide economic and social protections and soon came into question.

    Powers granted to the central government
    • Declare war and peace
    • Make treaties with foreign powers
    • Establish an army and navy
    • Appoint military officials
    • Borrowing money
    • Establish weights and measures
    • Hear disputes between states over trade and boundaries
    Powers DENIED to the central government
    • Could not raise funds for an army or navy
    • No power to tax or impose tariffs
    • No executive branch to enforce laws
    • No ability to regulate trade among the states
    • No power to force states to honor obligations
    • No authority to regulate the currency's value

    Sovereignty: The entity that designates the supreme power or authority of government and the authority of the state to govern itself or others. For example, in a monarchy, sovereignty is held by the King or Queen. In a democracy, sovereignty is held by the people through elected representatives.

    The US Constitution

    The Constitutional Convention in Philadelphia gathered to discuss these failures in 1787 and created a new constitution. Some of the key elements included:

    • Three Branches of Government:

      • Bi-cameral Legislative Branch - created through the Great Compromise

      • Executive Branch

      • Judicial Branch

    • The three-fifths compromise: The clause was created as a compromise over the delegation of population towards representation in the House of Representatives. At the time, all white people would count as one citizen toward the population count; all non-white individuals would count as three-fifths of a person towards the population count. This clause is removed after the passage of the 14th Amendment.

    • The Creation of the Amendment system to change the Constitution

    • The Ratification of the Bill of Rights - the first ten amendments to the Constitution

    US History The Constitutional Convention Illustration StudySmarterFig. 5 The Constitutional Convention Illustration

    The first presidents in US history: facts

    Let's look at the influence of the first presidents of America on the country's future.




    George Washington

    1789 - 1797
    • Nominated the First Chief Justice, John Jay
    • Established the First National Bank of the United States
    • Set up the cabinet system of advisors
    • Established the precedent of only serving two terms

    John Adams

    • Established the United States as a force in foreign power by ending the Quasi-War with France and the X-Y-Z Affair
    • Appointed John Marshall as Chief Justice

    Thomas Jefferson

    • Oversaw the Louisiana Purchase in 1803
    • Oversaw the Barbary Wars
    • Introduced the Embargo Act of 1807, which damaged the U.S. economy and laid the groundwork for the War of 1812 with England.

    James Madison

    • Commander in Chief during the War of 1812 against Britain - won the war and signed the Treaty of Ghent in 1814
    • The end of his term began the U.S. "Era of Good Feelings"

    James Monroe

    • The Treaty of 1818 ended boundary conflicts with Britain
    • Adams-Onis Treaty acquired Florida from Spain
    • Established the Monroe Doctrine
    • Missouri Compromise of 1820 passed, regulating slavery in western territories

    John Quincy Adams

    1825- 1829
    • Passed infrastructure legislation to build roads and canals connecting the states
    • Established treaties of reciprocity with many European nations

    Andrew Jackson

    • Founder of the Democratic Party
    • Established the first populist movement in U.S. politics known as Jacksonian Democracy
    • Established the U.S. Exploring Expedition
    • Signed and enforced the infamous Indian Removal Act

    American expansionism

    Through most of the 1800s, expansionism defined America’s ethos. The concept of manifest destiny gripped the young nation.

    Manifest Destiny

    Coined by a journalist in the 1820s. The ideological belief was that the United States's purpose was to control the North American continent and its sphere of influence.

    Critical events in American expansionism included:

    1803Louisiana Purchase The territory west of the Mississippi River was successfully purchased from Napoleon for $15 million. This doubled the size of the US. Due to its relatively low price and ease of negotiations, many Americans felt there was a divine influence in the proceedings.
    1812 - 14War of 1812 Victory in this war gave the US almost all of the remaining British territories in North America.
    1846 - 48 Mexican-American WarVictory in this war resulted in the Treaty of Guadalupe Hidalgo. The treaty forced Mexico to give up its land in the southwest.

    These events created a feeling that it was destiny to control the continent. If God did not want the U.S. to expand, Louisiana would not have been purchased so cheaply, and the wars would not have been so victorious.

    US History Map of US territorial expansions StudySmarterFig 6. US History Map of US territorial expansions

    Americans were motivated to move west by the possibilities it offered. For instance, the 1849 California Gold Rush and other precious mineral claims attracted hundreds of thousands of Americans. The establishment of the transcontinental railroad also solidified America’s claim to the land in the west. As more Americans moved, American Frontier culture defined itself.

    American Frontier

    The westward-moving border of the United States was characterized by American settlers' movement into these acquired territories.

    However, this land was not unoccupied, and Americans faced defiant opposition from Indigenous nations. The Indian Wars with the Sioux, Crow, and other nations devastated Indigenous societies.

    The federal government sanctioned much of the destruction, such as the Indian Removal Act of 1837. The US Army forced the Cherokee, Choctaw, Chickasaw, Creek, and Seminole tribes off their ancestral lands.

    Did you know? The forced journey of Indigenous Peoples off their lands was known as the Trail of Tears. A quarter of the Indigenous people on this journey did not survive.

    Expansionism profoundly influenced American economic, domestic, and foreign policy to close the Western frontier in the early 1900s.

    The American Civil War

    During American expansionism, one of the defining events of US history occurred - the 1861-5 American civil war between the North and South. What caused this war, how did it end, and how did this affect the future of the US?

    US History Battle of Gettysburg StudySmarterFig. 7 Battle of Gettysburg

    Causes of the Civil War

    The causes of the Civil War are complex and compounded upon each other, reaching a breaking point on 12th April 1861, when the South Carolina Militia opened fire on the Federal-controlled Fort Sumter. The table below shows some of the causes of the Civil War:

    Causes of the Civil War


    Union Perspective

    Confederate Perspective


    Increasingly against slavery

    The southern economy was reliant on slavery

    Growing Sectionalism

    Increasingly industrial economy - need for tariffs to protect American industry

    Agricultural economy - tariffs damaged their economy

    States' Rights

    Desire for a strong central government to regulate trade and commerce, and uphold minority rights

    Wanted to maintain authority over their citizens and have the right to abolish federal laws in their states

    Westward Expansion

    With every new territory to the west, the debate of if it would allow slavery or not became a nationally debated issue.

    The Election of 1860

    Abraham Lincoln won the northern states; John Breckinridge won the southern states, suggesting a divided nation. Many southerners feared Lincoln would use his Presidency to push through laws abolishing slavery and removing states' rights in the federal government.

    Union: Twenty northern states and many states in the west that remained in the United States during the American Civil War

    Confederacy: Also known as the Confederate States of America, consisting of 11 southern states that seceded from the control of the federal government of the United States, beginning with South Carolina in 1860

    Secession: withdrawing from membership of the federal government

    Tariff: tax on imports or exports

    Conduct of the Civil War

    The southern states fought for their right to retain enslaved persons and self-govern, whilst the northern states fought for the preservation of the Union and the liberation of enslaved labor in the south.

    The civil war battles saw the most casualties the U.S. has ever seen in warfare: approximately 360,000 Northern casualties and 260,000 Southern casualties. The Union forces were ultimately victorious on April 9th, 1865.

    Effects of the Civil War

    • Established the United States as a single sovereign entity

    • The emancipation of nearly four million enslaved Americans

    • Solidified the power and control of the central government over the states

    • Directly influenced the adoption of the following Amendments:

      • 13th Amendment: Ended the practice of slavery in the United States

      • 14th Amendment: All persons born or naturalized in the United States are U.S. Citizens - granted citizenship and protection under the Federal government to all freed enslaved persons

      • 15th Amendment: Protects the right to vote for all U.S. Citizens

    • Began the Era of Reconstruction

    The Reconstruction era (1865-77)

    After the war, the federal government faced the question: how would the confederate states be readmitted to the Union? The era of Reconstruction sought to answer this, with the key issue being the rights of newly freed enslaved persons.

    Reconstruction was divided into two phases:

    Presidential Reconstruction

    • After Abraham Lincoln was assassinated in 1865, Vice President Andrew Johnson took office as President.
    • He offered a pardon to all southerners who took an oath of allegiance to the Union, except for high-ranking Confederate officials.
    • Johnson required southern states to ratify the 13th Amendment while rejoining the Union.
    • The new governments in the South enjoyed quite a lot of freedom, allowing them to subjugate African Americans in other ways. Many Southern states created "black codes."

    US History Lincoln and Johnsond Union Cartoon StudySmarterFig. 8 Lincoln and Johnsond Union Cartoon

    Black Codes: a set of laws requiring Black people to sign yearly labor contracts to avoid being arrested, getting fined, or being forced to do unpaid labor

    Radical Reconstruction

    The need for reform in the south pitted the president against Congress. Political battles over the Freedman’s Bureau, the Civil Rights Act of 1866, and the 14th and 15th Amendments led to the first impeachment of a U.S. President in 1866.

    Radical Republicans then passed the Reconstruction Act of 1867, dividing the South into five military districts occupied by US troops. Republicans also demanded African American political participation in the South. Though white Southerners disagreed with Radical Reconstruction, it continued until 1877.

    Freedman's Bureau: An agency of the U.S. War Department established in 1865 to assist formerly enslaved people in obtaining relief, land, jobs, education, and equal protection under the law.

    Radical Reconstruction policies allowed African Americans various opportunities, especially in politics, but this changed when Reconstruction ended in 1877.

    Why did Reconstruction end?

    • National attention turned away from Reconstruction and towards economic recovery after the Depression of 1873.
    • White democrats used violence and intimidation tactics to regain political power in the South. The Ku Klux Klan was a large part of this.
    • The South introduced Jim Crow laws (legalized segregation) in the 1870s.
    • Reconstruction ended with the Presidential election of 1876 when Rutherford B. Hayes took office and withdrew federal troops from the South in 1877.

    Ku Klux Klan (KKK)

    A US white supremacist terrorist organization, formed in 1865 against Reconstruction, used intimidation tactics to prevent African-Americans from exercising their civil rights.

    Post-Reconstruction South

    At the end of Reconstruction, anti-African American violence and segregation exploded in the South. The Jim Crow laws threatened newly gained civil rights and legalized segregation.

    African Americans were barred from using the same public facilities as white Southerners. The Supreme Court upheld this idea of being separate but equal with the ruling of Plessy v. Ferguson in 1896. The Jim Crow era continued until the 1964 Civil Rights Act.

    The American Gilded Age



    Social Darwinism

    The theory that human beings are subject to the Darwinian law of natural selection i.e. survival of the fittest

    Laissez-Faire Capitalism

    The government does not interfere in the workings of the free market.

    Patronage System

    Hiring a person to a political position based on party (ie: democratic/republican) loyalty

    Political Machines

    A political practice of a party organization headed by a single leader or small group that controls enough votes to maintain control of a city or state.

    The 1870s to 1890s saw a complete economic, political, and industrial transformation. The period became known as the “Gilded Age” due to the ages' incredible prosperity tarnished with corruption and lack of ethics. The economy saw its largest and fastest rise to date, with the rapid expansion of cities, immigration, and technologies.

    The Gilded Age got its name from The Gilded Age: A Tale of Today, published by Mark Twain and Charles Dudley in 1873.

    The political concept of Social Darwinism justified wealth inequality.

    US History Twain 1974 The Gilded Age StudySmarterFig. 9 Twain 1974 The Gilded Age

    Laissez-faire capitalism enabled industrialists to increase their wealth quickly; they became known as both "captains of industry" and "robber barons." The Gilded Age was a period of vast wealth inequality, with money concentrated in the hands of the industrialists; workers’ discontent with this and the poor working conditions they faced ultimately led to strikes.

    Politics in the Gilded Age

    The Gilded Age was defined by materialism and political corruption. Industrial leaders often backed presidential candidates with the expectation of having complete control, leading to a corrupt government.

    • Elected presidents gave political positions to their supporters through the patronage system.
    • All presidents elected from 1876 to 1892 won with less than fifty percent of the popular vote.
    • Due to their ineffectiveness, corruption, and lack of impact, presidents elected during this time became known as the "forgotten presidents."

    The Gilded Age saw voter turnout sometimes exceeding 90% and narrow political elections between Republicans and Democrats. Political machines influenced the surge in voter turnout.

    The People's Party (aka Populist Party) emerged in 1891 to represent agricultural America and take down the large industrial monopolies. Seeing the appeal of the Populists, the Democrats began adopting the party's ideals, and the People's Party slowly integrated into the Democratic Party.

    US History Peoples Party at Columbus Nebraska StudySmarterFig. 10 Peoples Party at Columbus Nebraska

    The Gilded Age ended with the Panic of 1893, which caused an economic depression for the next four years. The ethical and industrial issues of the Gilded Age ushered in the Progressive Era.

    The Progressive Era

    The late 1890s to 1920s saw a sweeping social activism movement and political reform known as the Progressive Era. The People's Party's beliefs inspired the era's ideals in supporting the working class and abolishing monopolies. With the rapid industrialization of the country came:
    • the spread of poverty
    • terrible living conditions
    • lack of labor laws
    • domination of industrialist leaders

    Progressives wanted to fix all these problems.

    US History President Roosevelt StudySmarterFig. 11 President Roosevelt

    The presidents of the Progressive Era who followed this agenda were:

    • Theodore "Teddy" Roosevelt, Republican (1901-1909)
    • William Howard Taft, Republican (1909-1913)
    • Woodrow Wilson, Republican (1913-1921)

    Progressives also sought to eliminate government corruption that had been so prevalent throughout the Gilded Age. Progressivism aimed to end the monopolies’ grip on the economy and create healthy competition.

    The era also saw the passing of the eighteenth and nineteenth amendments:

    • The eighteenth amendment banned the sale and transportation of alcohol, known as prohibition.
    • The nineteenth gave women the right to vote.

    Progressives supported child labor laws, a shorter workday, minimum wages, and urban reform. The movement combatted injustices through the political organization, journalistic publications, and political activism.

    American imperialism

    When Americans declared independence from Britain in 1776, they sought to avoid the errors of the Old World, such as imperial overextension. However, in 1823, the United States endorsed the Monroe Doctrine, which effectively declared the Americas its exclusive sphere of influence to prevent further European colonization. At the same time, westward expansion under the banner of Manifest Destiny incorporated new territories and expelled their Indigenous inhabitants.

    By the end of the 19th century, the United States was using two methods to extend its global influence: commercial companies like the United Fruit Company to dominate parts of Latin America as “banana republics”, and military-political force. The latter included the U.S. acquisition of the Philippines colony (1899-1946) and the protectorate of Cuba (1898).

    The U.S. also annexed Hawaii (1898) and established itself as a power in the Pacific. These territorial acquisitions occurred within the context of the Spanish-American War (1898), a key turning point for American imperialism. The subsequent American occupation of Haiti (1915–1934) came shortly afterward.

    In the 20th century and beyond, the United States continued its imperialist trajectory through direct or indirect hegemonic means.

    Hegemony is the control of one state by another. This control may be exerted by different means, including military, economic, political, and cultural variants.

    US History United Fruit Company Steamship Line advertisement 1916 StudySmarterFig. 12 United Fruit Company Steamship Line advertisement 1916.

    America in World War I

    American involvement in WWI was initially uncertain as the country did not want to be drawn into large-scale military conflicts. President Wilson entered the war in April 1917, three years after it started, and Americans fought on the Western Front.

    Public opinion also favored neutrality until the sinking of Britain’s Lusitania—with Americans on board—by a German U-boat. Before its entry, the United States supplied the Allies, such as France and the U.K., with material aid. This war led to the significant expansion of the U.S. Armed Forces and the participation in the Paris Peace Conference (1919) as one of the victors.

    Therefore, America’s late entry into the First World War was a critical moment for international relations. Until the mid-to-late 19th century, the United States' foreign policy was generally isolationist. The Founding Fathers wanted to avoid the mistakes of the Old World, such as being entangled in many wars. Its 1823 Monroe Doctrine also sought to avoid war with major European players by preventing their colonization of the Western hemisphere. Yet, the Spanish-American War and American imperialism in Cuba, the Philippines, and Haiti ended the era of relative isolationism. The First World War solidified the American presence as an active participant in global affairs.

    The Roaring Twenties

    Three American leaders, President Harding (1921-1923), Coolidge (1923-1929), and Hoover (1929-1933) led the United States in the 1920s. All three leaders were Republicans who focused on domestic politics, such as business expansion through deregulation. After the devastation of the First World War in Europe, the United States embraced a relatively isolationist foreign policy and turned inward until World War II.US History, An advertising poster for the film Flaming Flappers (1925). A flapper—an urban woman breaking the rules—was a popular subject in the 1920s film industry. Source: Wikipedia Commons (U.S. public domain), Study Smarter.

    Fig. 13 Flaming Flappers Film advert

    The “roaring twenties” is a phrase that refers to the relative economic prosperity of that decade as well as the explosion of mass culture, including film, fashionable urban flappers, nightlife, consumer advertising, and jazz music. In an atmosphere of social freedom, many also defied the strict ban on alcohol during Prohibition (1920-1933).

    President Harding turned inward to domestic issues in politics as the U.S. recovered from the recession, WWI, and the Spanish flu pandemic. This decade primarily focused on economics, improving relations between labor and business, and lowering the national debt.

    Great Depression

    The optimism of the roaring twenties ended with the massive international economic downturn of the 1930s, known as the Great Depression. The era began with the stock market crash in the fall of 1929.

    Even in reasonably well-off western countries, the dire economic situation translated into broad-scale business closures, deflation due to financial collapse, unemployment, and destitution. At its worst, American GDP dropped by 30% and its industrial output by around 47%, with 20% unemployment.

    By the mid-1930s, the United States began showing gradual improvement. President Franklin D. Roosevelt initiated several measures as part of his New Deal and its government programs, such as the Works Progress Administration (WPA), to stabilize the economy.

    However, it was not until 1942—during the Second World War—that the American economy reached pre-Depression levels and continued to grow. The shared traumatic experience of living through the Great Depression produced notable works of literature such as John Steinbeck’s award-winning The Grapes of Wrath (1939).

    Deflation is an economic phenomenon when the price of things drops. Deflation is the opposite of inflation.

    GDP (gross domestic product) accounts for the economic production—all the goods and services—in a country over a defined period.

    US History "World's Highest Standard of Living." Photo by Margaret Bourke-White StudySmarterFig. 14 "World's Highest Standard of Living." Photo by Margaret Bourke-White

    Interwar Foreign Policy

    Overall, the interwar period was one when the United States faced inward and focused on domestic issues—with some notable exceptions.

    • Despite entering the Great War (WWI) in late 1917, the United States was one of the Big Four at the Paris Peace Conference (1919).
    • The aftermath of the war left defeated Germany with significant postwar reparations.
    • As a result, the United States introduced two consecutive measures, the Dawes Plan (1924) and the Young Plan (1929), to facilitate German recovery. These measures stabilized the German currency and refinanced its payments through loans.
    • Another issue related to WWI was the Russian Revolution (1917) which ultimately led to the establishment of the Soviet Union. The United States did not recognize the USSR until 1933, largely because of its communist ideology.
    • The rise of Nazi Germany (1933) and Japanese imperial expansion in Asia made international relations more complex and difficult.
    • Through initiatives such as the Neutrality Act (1935), the United States sought to avoid entanglements in international politics.

    America in World War II

    The Second World War (1939-1945) was fought by much of the world on almost every continent. Its casualties measured in the dozens of millions, with the USSR alone losing 27 million lives and massive infrastructural damage in every military theater.

    Despite an attempt at neutrality in the 1930s, the Pearl Harbor attack by imperial Japan in December 1941 on the United States led the US to join the Allied side (the Soviet Union, Britain, and others). Before its entry, the U.S. had offered the USSR material support through the Lend-Lease Act after Nazi Germany attacked the USSR in June 1941.

    The Lend-Lease Act was a piece of legislation that allowed the American government to provide supplies to various countries during WWII by leasing or lending instead of selling.

    The USSR bore the brunt of the fighting on the Eastern Front and was responsible for 80% of Nazi German losses overall. The United States participated in the European theater, particularly the Normandy landing (1944), and the Pacific theater, such as the Battle of Midway (1942) and the Battle of Iwo Jima (1945).

    In one of the darkest moments of the war, President Truman (1945-1953) ordered the nuclear attacks on the Japanese cities of Hiroshima and Nagasaki (August 1945) despite the imminence of the Japanese surrender. Ultimately, fueled by military victories and the economic boost of wartime industries at home, the United States emerged as a true superpower following this conflict.

    US History Nagasaki Bomb Cloud StudySmarterFig. 15 Nagasaki Bomb Cloud

    America in the Cold War and beyond

    The period from the 1950s onward became known as the American Century because the United States was able to dominate much of the world politically, militarily, economically, socially, and culturally. Post-war Europe slowly reinvented itself with the help of the American-led Marshall Plan (1948-1951), which gave economic and other assistance to rebuild the war-torn nations.

    However, its WWII ally and ideological rival, the Soviet Union, rose to superpower status. To counter the USSR's communism, President Truman articulated the Truman Doctrine (1947) as a deterrence strategy all around the globe. Long gone were the days of American isolationism.

    The Truman Doctrine was announced by President Harry Truman on 12th March 1947 and pledged to support countries with a new, hardline foreign policy against the spread of communism. It specified the support granted by the US to Greece and Turkey amidst their struggles against communism.

    The United States engaged in multiple military conflicts during the Cold War to prevent the spread of communism, including the Korean War (1950-1953) and the Vietnam War (1955-1975). The Vietnam War was unpopular with many Americans due to human rights violations, and the US ultimately failed to contain communism in Vietnam.

    The world became bipolar—split into two blocs, especially after China (1949) and Cuba (1959) had successful communist revolutions. Each Bloc had a respective military alliance: America’s North Atlantic Treaty Organization (NATO) and the Soviet Union’s Warsaw Pact.

    In the nuclear age, this rivalry came dangerously close to the point of no return - the Cuban Missile Crisis (1962) saw the world on the brink of nuclear war.

    The Soviet Union gradually lost power in its Bloc, initiating the fall of the Berlin Wall (1989) and the USSR's collapse (1991). For a time, the United States interpreted this as a victory in the Cold War, becoming the sole global superpower.

    Theorist Francis Fukuyama declared this period the end of history.

    After the Cold War

    The United States felt emboldened to participate in wars in the Middle East and Central Asia, particularly after the 9/11 terrorist attack on its soil on September 11, 2001. However, its invasions of Iraq (2003-2011) and Afghanistan (2001-2021), which lasted for years, did not succeed, destabilizing and devastating those regions.

    Today, the United States is dealing with a rapidly changing world. Domestically, the country is a society of contradictions—from racial tensions to economic inequalities. Internationally, the United States remains one of the most influential powers.

    US History - Key Takeaways

    • The American Revolution lasted eight years and resulted in independence from the British.
    • After the creation of the United States, Congress ratified the Articles of Confederation, which created a purposefully weak central government designed to give the individual states of America more sovereignty.
    • The Constitutional Convention in Philadelphia gathered to discuss the failures in 1787 of the Articles and ended up creating a new constitution.
    • Through most of the 1800s, expansionism defined America’s ethos. The concept of manifest destiny gripped the young nation.
    • During American expansionism, one of the defining events of US history occurred - the 1861-5 American civil war between the North and South.
    • After the war, the federal government created policies to govern and rebuild the south called Reconstruction.
    • At the end of Reconstruction, anti-African American violence and segregation exploded in the South. The JimCrow laws threatened newly gained civil rights and legalized segregation.
    • The Gilded Age was defined by materialism and political corruption. Industrial leaders often backed presidential candidates with the expectation of having complete control, leading to a corrupt government.
    • The “roaring twenties” is a phrase that refers to the relative economic prosperity of that decade as well as the explosion of mass culture, including film, fashionable urban flappers, nightlife, consumer advertising, and jazz music.
    • Between the late 19th and early 20th centuries, American foreign policy turned away from isolationism and toward imperialism and participation in wars, including the Spanish-American War and the First World War.
    • The United States rose to superpower status after the Second World War, as did the Soviet Union. This superpower rivalry split the world into two blocs (bipolarity) for the next four decades of the Cold War.

    Fig. 4 Declaration of Independence

    Frequently Asked Questions about US History

    What is the longest war in U.S. History? 

    The longest war in U.S. History was the War in Afghanistan which lasted from 2001 to 2021. The war was an international conflict triggered by the Taliban's attacks on the World Trade Center on September 11, 2001. 

    What was the U.S. called before 1776? 

    The U.S. was known as the thirteen colonies prior to 1776 and was under British authority. However, after the American Revolution in 1776, the Continental Congress officially changed the colonies' name to the United States.  

    What happened in 1776 in the United States? 

    In 1776 the thirteen colonies went to war with Britain. The American Revolution came to an end in 1776 with an American victory and the colonies officially formed the United States. 

    When did U.S. History actually begin? 

    U.S. History officially began after 1776 with the signing of the Declaration of Independence which declared the colonies free from British authority. 

    What is U.S. History? 

    U.S. History is the culmination of the social, political, cultural, and ideological events that influenced the formation of the country since 1776. 

    Indigenous Nations populated pre-colonial America until European countries began colonization efforts in the sixteenth century. For example, Britain began colonizing the area in 1607 which led to the formation of the thirteen colonies. Then, in the late eighteenth century, rebellious sentiment grew within the colonies and the American Revolutionary War broke out in 1775. After the war, the thirteen colonies won their independence from Britain and the Continental Congress officially named the colonies the United States in 1776. The United States officially emerged as a world power during the Spanish-American War in 1898 when Spain and the U.S. reached a cease-fire agreement. The Spanish-American War launched the U.S. military onto the world stage.  

    Test your knowledge with multiple choice flashcards

    What year were the Lincoln Douglas debates?

    How many debates were held in total?

    In what state did the debates take place?


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    Team US History Teachers

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