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AP U.S. History Unit 7: Period 7: 1890-1945

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: April 13, 2026

Unit Big Picture

Spanning from 1890 to 1945, this period tracks the United States' turbulent journey to becoming a global superpower. The era begins with the nation grappling with the social and economic consequences of industrialization, leading to the domestic reforms of the Progressive Era. This internal focus was repeatedly interrupted by global conflicts, including the Spanish-American War and two World Wars, which ultimately propelled the U.S. into a position of international leadership. The period concludes with the U.S. emerging from the Great Depression and World War II with a vastly more powerful federal government and a dominant role in a new world order.

Core Threads

Thread 1: The Role of Government in Society

  • Debates over the government's role in regulating the economy and society intensified, from Progressive-era trust-busting and social reforms to the New Deal's direct intervention during the Great Depression.

  • Wartime crises, particularly World War I and World War II, dramatically expanded federal power over industrial production, national resources, and individual civil liberties, setting new precedents for government authority.

Thread 2: America's Role in the World

  • The nation transitioned from a policy of continental expansion to one of overseas imperialism, sparking foundational debates between imperialists and anti-imperialists over America's global responsibilities.

  • After initial reluctance and a period of interwar isolationism, the U.S. ultimately entered two world wars, with its participation in World War II cementing its status as a dominant military and diplomatic power.

Timeline (Compact)

YearEvent
1898Spanish-American War begins
1917U.S. enters World War I
192019th Amendment grants women's suffrage
1929Stock Market Crash triggers Great Depression
1933Franklin D. Roosevelt begins New Deal
1941Attack on Pearl Harbor; U.S. enters WWII
1945End of World War II

Turning Points

Trigger (Precondition)Event (Year)Why It Mattered
Economic motives for new markets and the "closing" of the frontier.Spanish-American War (1898)Marked the U.S. emergence as a world power with overseas territories, ending its relative isolation.
Unstable 1920s economy and weak financial regulations.The Great Depression (begins 1929)Led to the New Deal, fundamentally altering the role and size of the federal government in the economy.
Axis aggression challenging U.S. isolationism; direct attack on U.S. soil.U.S. Entry into WWII (1941)Ended the Great Depression, propelled the U.S. to global superpower status, and set the stage for the Cold War.

Unit Evidence Bank

  1. Progressive Era: A period of widespread social activism and political reform (c. 1890s–1920s) that sought to address problems caused by industrialization, urbanization, and political corruption.

  2. Spanish-American War (1898): A conflict that ended Spanish colonial rule in the Americas and resulted in U.S. acquisition of territories, signaling America's rise as an imperial power.

  3. Theodore Roosevelt: A Progressive president whose "Square Deal" policies included trust-busting and conservation, and whose foreign policy was marked by assertive international engagement.

  4. Woodrow Wilson: A Progressive president who led the U.S. during World War I and championed the creation of the League of Nations to promote international peace.

  5. Harlem Renaissance: An intellectual and cultural revival of African American music, art, and literature centered in Harlem, New York City, during the 1920s, which celebrated Black culture and identity.

  6. Great Depression: The severe worldwide economic crisis of the 1930s. In the U.S., it led to mass unemployment and hardship, prompting an unprecedented government response.

  7. New Deal: A series of programs and reforms enacted under President Franklin D. Roosevelt. It aimed to provide economic relief, recovery, and reform, and greatly expanded the scope of the federal government.

  8. Franklin D. Roosevelt (FDR): The president who led the nation through the Great Depression and World War II, fundamentally reshaping American government through his New Deal policies and wartime leadership.

  9. Pearl Harbor: The surprise military strike by Japan on a U.S. naval base on December 7, 1941, which led to the United States' formal entry into World War II.

  10. Japanese American Internment: The forced relocation and incarceration of people of Japanese ancestry from the West Coast during World War II, a policy justified by national security concerns that raised major civil liberties questions.

Topic Navigator

Topic TitleWhat This Adds (≤10 words)
7.1: Contextualizing Period 7Setting the stage for a new American era.
7.2: Imperialism: DebatesArguments for and against overseas expansion.
7.3: The Spanish-American WarAmerica's arrival as a global military power.
7.4: The ProgressivesDomestic reforms addressing industrial society's problems.
7.5: World War I: Military and DiplomacyU.S. entry and Wilson's vision for peace.
7.6: World War I: Home FrontMobilizing the nation and restricting civil liberties.
7.7: 1920s: InnovationsNew technologies changing communication and daily life.
7.8: 1920s: Cultural and Political ControversiesClashes over immigration, religion, and modern values.
7.9: The Great DepressionCauses and effects of the economic collapse.
7.10: The New DealFDR's government response to the Depression.
7.11: Interwar Foreign PolicyThe tension between isolationism and internationalism.
7.12: World War II: MobilizationThe home front effort to win the war.
7.13: World War II: MilitaryKey strategies and battles of the U.S. military.
7.14: Postwar DiplomacyThe end of the war and new global alignments.
7.15: Comparison in Period 7Analyzing patterns across the entire 1890-1945 period.

Exam Skills Focus

  • Causation: Economic instability and global conflict led to a dramatic expansion of federal government power and a redefinition of its role in American life.

  • Comparison: Compare the motivations for U.S. entry into World War I versus World War II, and the different visions for the postwar world that resulted.

  • CCOT: The U.S. transitioned from an isolationist foreign policy to one of global leadership, while debates over the balance between national security and civil liberties remained a persistent issue during wartime.

Common Misconceptions & Clarifications

  • Misconception: The 1920s was a time of universal prosperity. → Clarification: While new consumer industries boomed, many farmers and workers in traditional industries faced significant economic hardship throughout the decade.

  • Misconception: The New Deal ended the Great Depression. → Clarification: The New Deal provided significant relief and lasting reforms, but full economic recovery was not achieved until the mass industrial mobilization for World War II.

  • Misconception: The U.S. was completely isolated before WWII. → Clarification: While official policy was isolationist, the U.S. engaged in significant international diplomacy and provided economic aid to Allied nations before formally entering the war.

One-Paragraph Summary

From 1890 to 1945, the United States underwent a profound transformation from a continental nation to a global superpower. This era was defined by cycles of reform, reaction, and crisis, including the Progressive movement's attempts to regulate industrial capitalism and the New Deal's expansion of the federal government to combat the Great Depression. The nation's role in the world shifted dramatically, from the imperialist ventures of the Spanish-American War to a reluctant entry into World War I, followed by a period of interwar isolationism that was shattered by the attack on Pearl Harbor. By the end of World War II, the U.S. had assumed a dominant position in global affairs, with a powerful central government and an economy poised for postwar prosperity.