The basics
Time period: 1890–1945 (the rise of America as a global superpower)
Exam weight: About 10–17% of the AP US History exam
The big question: How did the U.S. transform from an isolated republic into a global superpower with an activist federal government — through reform, depression, and two world wars?
Key topics at a glance
Imperialism & the Spanish-American War
The Spanish-American War (1898) gave the U.S. Puerto Rico, Guam, the Philippines, and control of Cuba; the Open Door Policy secured access to China.
The Progressive Era
Muckrakers exposed abuses; Theodore Roosevelt's Square Deal busted trusts and regulated business; Constitutional amendments (16th income tax, 17th direct senate election, 18th Prohibition, 19th women's suffrage) transformed government.
World War I
Triggered by U-boats and the Zimmermann Telegram; Wilson's Fourteen Points shaped peace talks; Senate rejected the Treaty of Versailles and the League of Nations.
Red Scare & Nativism
Post-WWI Palmer Raids targeted suspected radicals; the National Origins Act (1924) drastically restricted immigration from Southern/Eastern Europe and banned most Asians.
The Roaring Twenties
The Harlem Renaissance, Prohibition, the Scopes Trial, jazz, flappers, consumer culture — but also the Klan's resurgence and intense cultural conflicts.
The Great Depression
The 1929 stock market crash triggered economic collapse; the Dust Bowl devastated the Plains; 25% unemployment; Hoover's response failed.
The New Deal
FDR's "3 R's" — Relief (CCC, WPA), Recovery (NIRA, AAA), Reform (Social Security, Wagner Act) — built the modern welfare state.
World War II
Pearl Harbor (Dec 7, 1941) brought the U.S. into the war; total mobilization ended the Depression; Japanese internment; atomic bombs on Hiroshima and Nagasaki ended the war.
The key terms you must know
- Progressivism — Early-1900s reform movement attacking industrial-era abuses; produced the 16th–19th Amendments and Theodore Roosevelt's Square Deal.
- Spanish-American War — 1898 war that made the U.S. a global empire (Puerto Rico, Guam, Philippines, Cuba).
- Treaty of Versailles — 1919 treaty Senate rejected because of opposition to the League of Nations; U.S. retreated to isolationism.
- New Deal — FDR's 1933+ program of Relief, Recovery, and Reform; built the modern welfare state via Social Security and labor protections.
- Pearl Harbor — Dec 7, 1941 Japanese attack that brought the U.S. into WWII and ended the Depression through wartime mobilization.