Civil War and industrialization
Tensions between slave and free states mounted with increasing disagreements over the relationship between the state and federal governments and violent conflicts over the expansion of slavery into new states. Abraham Lincoln, candidate of the largely antislavery Republican Party, was elected president in 1860. Before he took office, seven slave states declared their secession from the United States, forming the Confederate States of America. The federal government maintained secession was illegal, and with the Confederate attack upon Fort Sumter, the American Civil War began and four more slave states joined the Confederacy. The Union freed Confederate slaves as its army advanced through the South. Following the Union victory in 1865, three amendments to the U.S. Constitution ensured freedom for the nearly four million African Americans who had been slaves,[26] made them citizens, and gave them voting rights. The war and its resolution led to a substantial increase in federal power.[27]
After the war, the assassination of President Lincoln Radical Republican (USA) Reconstruction policies aimed at reintegrating and rebuilding the Southern states while ensuring the rights of the newly freed slaves. The disputed 1876 presidential election resolved by the Compromise of 1877 ended Reconstruction; Jim Crow laws soon disenfranchised many African Americans. In the North, urbanization and an unprecedented influx of immigrants hastened the country's industrialization. The wave of immigration, which lasted until 1929, provided labor for U.S. businesses and transformed American culture. High tariff protections, national infrastructure building, and new banking regulations encouraged industrial growth. The 1867 Alaska purchase from Russia completed the country's mainland expansion. The Wounded Knee massacre in 1890 was the last major armed conflict of the Indian Wars. In 1893, the indigenous monarchy of the Pacific Kingdom of Hawaii was overthrown in a coup led by American residents; the archipelago was annexed by the United States in 1898. Victory in the Spanish-American War that same year demonstrated that the United States was a major world power and resulted in the annexation of Puerto Rico and the Philippines.[28] The Philippines gained independence a half-century later; Puerto Rico remains a commonwealth of the United States.
World War I, Great Depression, and World War II
At the outbreak of World War I in 1914, the United States remained neutral. Americans sympathized with the British and French, although many citizens, mostly Irish and German, opposed intervention.[29] In 1917, the United States joined the Allies, turning the tide against the Central Powers. Reluctant to be involved in European affairs, the Senate did not ratify the Treaty of Versailles, which established the League of Nations. The country pursued a policy of unilateralism, verging on isolationism.[30] In 1920, the women's rights movement won passage of a constitutional amendment granting women's suffrage. In part due to the service of many in the war, Native Americans gained U.S. citizenship in the Indian Citizenship Act of 1924.
During most of the 1920s, the United States enjoyed a period of unbalanced prosperity as farm profits fell while industrial profits grew. A rise in debt and an inflated stock market culminated in the 1929 crash that triggered the Great Depression. After his election as president in 1932, Franklin D. Roosevelt responded with the New Deal, a range of policies increasing government intervention in the economy. The Dust Bowl of the mid-1930s impoverished many farming communities and spurred a new wave of western migration. The nation would not fully recover from the economic depression until the industrial mobilization spurred by its entrance into World War II. The United States, effectively neutral during the war's early stages after the Nazi invasion of Poland in September 1939, began supplying materiel to the Allies in March 1941 through the Lend-Lease program.
On December 7, 1941, the United States joined the Allies against the Axis powers after a surprise attack on Pearl Harbor by Japan. World War II cost far more money than any other war in American history,[31] but it boosted the economy by providing capital investment and jobs, while bringing many women into the labor market. Among the major combatants, the United States was the only nation to become richer—indeed, far richer—instead of poorer due to the war.[32] Allied conferences at Bretton Woods and Yalta outlined a new system of international organizations that placed the United States and Soviet Union at the center of world affairs. As victory was achieved in Europe, a 1945 international conference held in San Francisco produced the United Nations Charter, which became active after the war.[33] The United States, having developed the first nuclear weapons, used them on the Japanese cities of Hiroshima and Nagasaki in August. Japan surrendered on September 2, ending the war.[34]
Superpower
The United States and Soviet Union jockeyed for power after World War II during the Cold War, dominating the military affairs of Europe through NATO and the Warsaw Pact. The United States promoted liberal democracy and capitalism, while the Soviet Union promoted communism and a centrally planned economy. The Soviet Union supported dictatorships, as did the United States, and both engaged in proxy wars. United States troops fought Communist Chinese forces in the Korean War of 1950–53. The House Un-American Activities Committee pursued a series of investigations into suspected leftist subversion, while Senator Joseph McCarthy became the figurehead of anticommunist sentiment.
The Soviet Union launched the first manned spacecraft in 1961, prompting U.S. efforts to raise proficiency in mathematics and science and President John F. Kennedy's call for the country to be first to land "a man on the moon," achieved in 1969.[35] Kennedy also faced a tense nuclear showdown with Soviet forces in Cuba. Meanwhile, America experienced sustained economic expansion. A growing civil rights movement headed by prominent African Americans, such as Martin Luther King, Jr., fought segregation and discrimination, leading to the abolition of Jim Crow laws. Following Kennedy's assassination in 1963, the Civil Rights Act of 1964 was passed under President Lyndon B. Johnson. Johnson and his successor, Richard Nixon, expanded a proxy war in Southeast Asia into the unsuccessful Vietnam War.
As a result of the Watergate scandal, in 1974 Nixon became the first U.S. president to resign, rather than be impeached on charges including obstruction of justice and abuse of power; he was succeeded by Gerald Ford. During the Jimmy Carter administration in the late 1970s, the U.S. economy experienced stagflation. The election of Ronald Reagan as president in 1980 marked a significant rightward shift in American politics, reflected in major changes in taxation and spending priorities.[36] In the late 1980s and 1990s, the Soviet Union's power diminished, leading to its collapse. The leadership role taken by the United States and its allies in the United Nations–sanctioned Gulf War, under President George H. W. Bush, and later the Yugoslav wars helped to preserve its position as the world's last remaining superpower. The longest economic expansion in modern U.S. history—from March 1991 to March 2001—encompassed the administration of President Bill Clinton.[37] In 1998, Clinton was impeached by the House on charges relating to a civil lawsuit and a sexual scandal, but was acquitted by the Senate and remained in office.
The controversial presidential election of 2000 was resolved by a Supreme Court decision that effectively awarded the presidency to Texas governor George W. Bush, son of George H. W. Bush. On September 11, 2001, terrorists struck the World Trade Center in New York City and The Pentagon near Washington, D.C., killing nearly three thousand people. In the aftermath, President Bush launched the War on Terrorism under a military philosophy stressing preemptive war now known as the Bush Doctrine. In late 2001, U.S. forces led a NATO invasion of Afghanistan, removing the Taliban government and al-Qaeda terrorist training camps. Taliban insurgents continue to fight a guerrilla war against the NATO-led force. In 2002, the Bush administration began to press for regime change in Iraq on controversial grounds. Lacking the support of NATO, Bush formed a Coalition of the Willing and the U.S. invaded Iraq in 2003, removing President Saddam Hussein from power. Although facing both external[38] and internal[39] pressure to withdraw, the United States maintains its military presence in Iraq.
