What you'll learn
Period 7 of AP US History (1890–1945) covers America's transformation into a modern industrial and world power, from the Progressive Era through two world wars and the Great Depression. This is one of the most heavily tested periods on the exam. For AP US History you need to understand the causes and effects of imperialism, the Progressive movement, the two world wars and America's changing role abroad, the boom of the 1920s, the Great Depression and the New Deal. This guide covers the major developments in order, the key debates historians and Americans had at the time, and how to use this period in the exam's essays. By the end you should be able to explain the main continuities and changes across the period and connect them to broader themes.
Key terms and definitions
Imperialism — A policy of extending a country's power by acquiring territory or influence abroad.
Progressivism — An early 20th-century reform movement aiming to correct the problems of industrialisation and corruption.
Isolationism — The policy of avoiding involvement in the affairs of other countries.
The New Deal — Franklin Roosevelt's programs to provide relief, recovery and reform during the Great Depression.
Great Migration — The movement of African Americans from the rural South to northern cities.
Laissez-faire — The idea that government should not interfere in the economy.
Federal power — The authority of the national government, which expanded greatly in this period.
Total war — A war in which a nation mobilises its whole economy and population.
Core concepts
Imperialism and the Spanish-American War
By the 1890s, the United States was looking beyond its borders for markets, resources and influence. The Spanish-American War (1898) marked America's emergence as a world power, gaining territories such as the Philippines, Puerto Rico and Guam. This sparked a debate between imperialists, who argued expansion brought economic and strategic benefits, and anti-imperialists, who argued it contradicted America's founding principles of self-government. This tension between involvement abroad and traditional isolationism runs through the whole period.
The Progressive Era
Progressivism was a broad reform movement responding to the problems of rapid industrialisation: corruption, poor working conditions, unsafe food, and the power of big business. Progressives pushed for reforms such as regulating monopolies, improving factory conditions, and expanding democracy through measures like the direct election of senators. Presidents Theodore Roosevelt and Woodrow Wilson expanded federal power to regulate the economy. Progressivism also included the movement for women's suffrage, achieved with the 19th Amendment in 1920.
World War I and its aftermath
The United States initially stayed neutral in World War I, reflecting its isolationist tradition, but entered in 1917. The war expanded federal power over the economy and society. Afterwards, Wilson promoted the League of Nations, but the Senate rejected membership, and the country turned back towards isolationism in the 1920s. The war also accelerated the Great Migration of African Americans to northern cities in search of work.
The 1920s
The 1920s saw economic boom, consumer culture and social change, including new roles for women and the cultural flourishing of the Harlem Renaissance. But the decade also had deep tensions: immigration was restricted, Prohibition was introduced, and there was a resurgence of nativism. The boom was built partly on credit and speculation, which left the economy vulnerable.
The Great Depression and the New Deal
The Great Depression began with the Wall Street Crash of 1929 and brought mass unemployment and hardship. Franklin Roosevelt's New Deal responded with programs for relief, recovery and reform, greatly expanding the role of the federal government in the economy and in people's lives. The New Deal reshaped the relationship between citizens and government, even though it did not fully end the Depression. It generated debate between those who thought government should do more and those who thought it had already gone too far.
World War II
America again began in isolation but was drawn into World War II after the attack on Pearl Harbor in 1941. The war ended the Depression by mobilising the entire economy — a total war effort that brought millions of women and minorities into the workforce. Victory established the United States as a global superpower, setting the stage for its dominant role after 1945. The war also raised difficult issues at home, including the internment of Japanese Americans.
African Americans across the period
The experience of African Americans is a major thread through Period 7. The Great Migration saw hundreds of thousands move from the rural South to northern industrial cities during and after World War I, seeking work and escaping segregation and violence, though they often met discrimination in the North too. The 1920s brought the Harlem Renaissance, a flourishing of African American art, music and literature. World War II opened new industrial jobs and military service, and the contradiction between fighting for freedom abroad while facing segregation at home helped lay the groundwork for the later civil rights movement. Tracing this experience is a strong way to show change and continuity in an essay.
Changing roles of women
Women's roles also changed significantly. The Progressive Era's campaign for suffrage succeeded with the 19th Amendment in 1920, giving women the vote. The 1920s saw new social freedoms for some women. During both world wars, and especially World War II, large numbers of women entered the workforce to replace men who had gone to fight, taking on industrial jobs symbolised by figures such as "Rosie the Riveter". Although many of these gains were rolled back after the wars, they marked lasting shifts in expectations. Using women's changing roles as evidence strengthens essays on social change.
Worked examples
Example 1: Identifying a continuity
Identify one continuity across Period 7 in America's foreign policy. A continuing tension between isolationism and involvement abroad. The US repeatedly tried to stay out of world affairs (before both world wars, and in rejecting the League of Nations) but was ultimately drawn into global conflicts and emerged as a world power.
Example 2: Explaining the growth of federal power
Explain how the role of the federal government changed during Period 7. Federal power expanded greatly. Progressives used it to regulate business and improve conditions; both world wars expanded government control of the economy; and the New Deal made the federal government responsible for economic security in ways not seen before, marking a major shift from laissez-faire.
Example 3: Causation in the New Deal
Explain why the New Deal represented a turning point. Before the Depression, the government largely followed laissez-faire. The New Deal made the federal government take active responsibility for relief, jobs and economic regulation, permanently expanding its role and changing citizens' expectations of what government should do.
Example 4: Connecting war and social change
Explain one way World War II changed American society. The total-war effort brought large numbers of women and minorities into the industrial workforce, changing employment patterns and contributing to later movements for equality, even though many gains were rolled back after the war.
Common mistakes and how to avoid them
A common error is treating this period as a list of separate events. The exam rewards connecting them through themes such as the growth of federal power, America's changing role abroad, and social change. Always link events to a bigger argument.
Students often oversimplify the New Deal as "ending the Depression". It provided relief and reform and expanded government, but it was World War II that fully restored the economy. Be precise about this.
Another mistake is ignoring the debates of the time. For each development — imperialism, the New Deal, entering the wars — there were Americans on both sides, and showing that you understand the disagreement strengthens an essay.
When writing about the wars, do not forget the home front: the wars changed the economy, the workforce, and the role of government, not just foreign policy.
Finally, avoid vague generalisations. Support points with specific evidence — the Spanish-American War, the 19th Amendment, the Wall Street Crash, Pearl Harbor — to reach the higher bands.
Exam technique for "Period 7: 1890–1945"
This period appears frequently in the essay questions, so be ready to argue about change and continuity, causation, and the growth of federal power. Build your essays around a clear, defensible thesis and support it with specific evidence from across the period.
For long essays, use the themes: American and national identity, politics and power, work and economy, and America in the world. These let you connect the Progressive Era, the wars, and the New Deal into a single argument.
Always contextualise: place your argument in the wider trends of industrialisation and America's rise as a world power. Use specific dates, laws and events as evidence, and address complexity by acknowledging the debates and limits of each development.
Quick revision summary
- Imperialism and the Spanish-American War (1898) made the US a world power and sparked debate over expansion.
- Progressivism reformed industrial society and expanded federal regulation; women gained the vote (19th Amendment, 1920).
- World War I: neutrality then entry (1917); afterwards the US rejected the League of Nations and returned to isolationism.
- The 1920s brought boom, consumerism and the Harlem Renaissance but also nativism and economic fragility.
- The Great Depression and New Deal greatly expanded the federal government's role in the economy.
- World War II ended the Depression, transformed society, and made the US a global superpower.