ahead of Canada.[16] The United States also possesses several insular territories scattered around the West Indies (e.g., the commonwealth of Puerto Rico) and the Pacific (e.g., Guam). The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountains divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest. The Mississippi-Missouri River, the world's fourth longest river system, runs mainly north-south through the heart of the country. The flat, fertile prairie land of the Great Plains stretches to the west. The Rocky Mountains, at the western edge of the Great Plains, extend north to south across the continental United States, reaching altitudes higher than 14,000 feet (4,300 m) in Colorado.[17] The area to the west of the Rocky Mountains is dominated by the rocky Great Basin and deserts such as the Mojave. The Sierra Nevada range runs parallel to the Rockies, relatively close to the Pacific coast. At 20,320 feet (6,194 m), Alaska's Mount McKinley is the country's tallest peak. Active volcanoes are common throughout the Alexander and Aleutian Islands, and the entire state of Hawaii is built upon tropical volcanic islands. The supervolcano underlying Yellowstone National Park in the Rockies is the continent's largest volcanic feature.[18] Because of the United States' large size and wide range of geographic features, nearly every type of climate is represented. The climate is temperate in most areas, tropical in Hawaii and southern Florida, polar in Alaska, semi-arid in the Great Plains west of the 100th meridian, desert in the Southwest, Mediterranean in Coastal California, and arid in the Great Basin. Extreme weather is not uncommon—the states bordering the Gulf of Mexico are prone to hurricanes, and most of the world's tornadoes occur within the continental United States, primarily in the Midwest.[19] Environment The bald eagle has been the national bird of the United States since 1782 Main article: Environment of the United States U.S. plant life is very diverse; the country has more than 17,000 identified native species of flora.[20] More than 400 mammal, 700 bird, 500 reptile and amphibian, and 90,000 insect species have been documented.[21] The Endangered Species Act of 1973 protects threatened and endangered species and their habitats, which are monitored by the U.S. Fish and Wildlife Service. The U.S. has fifty-eight national parks and hundreds of other federally managed parks, forests, and wilderness areas.[22] Altogether, the U.S. government regulates 28.8% of the country's total land area.[23] Most such public land comprises protected parks and forestland, though some federal land is leased for oil and gas drilling,[24] mining, or cattle ranching. The energy policy of the United States is widely debated; many call on the country to take a leading role in fighting global warming.[25] The United States is currently the second largest emitter, after the People's Republic of China, of carbon dioxide from the burning of fossil fuels.[26] History Main article: History of the United States Native Americans and European settlers Main articles: Native Americans in the United States, European colonization of the Americas, and Thirteen Colonies The indigenous peoples of the U.S. mainland, including Alaska Natives, are thought to have migrated from Asia. They began arriving at least 12,000 and as many as 40,000 years ago.[27] Several indigenous communities in the pre-Columbian era developed advanced agriculture, grand architecture, and state-level societies. In 1492, Genoese explorer Christopher Columbus, under contract to the Spanish crown, reached several Caribbean islands, making first contact with the indigenous population. In the years that followed, the majority of the indigenous American peoples were killed by epidemics of Eurasian diseases.[28] The Mayflower transported Pilgrims to the New World in 1620, as depicted in William Halsall's The Mayflower in Plymouth Harbor, 1882 On April 2, 1513, Spanish conquistador Juan Ponce de León landed on what he called "La Florida"—the first documented European arrival on what would become the U.S. mainland. Of the colonies Spain established in the region, only St. Augustine, founded in 1565, remains. Later Spanish settlements in the present-day southwestern United States drew thousands through Mexico. French fur traders established outposts of New France around the Great Lakes; France eventually claimed much of the North American interior as far south as the Gulf of Mexico. The first successful English settlements were the Virginia Colony in Jamestown in 1607 and the Pilgrims' Plymouth Colony in 1620. The 1628 chartering of the Massachusetts Bay Colony resulted in a wave of migration; by 1634, New England had been settled by some 10,000 Puritans. Between the late 1610s and the American Revolution, an estimated 50,000 convicts were shipped to England's, and later Great Britain's, American colonies.[29] Beginning in 1614, the Dutch established settlements along the lower Hudson River, including New Amsterdam on Manhattan Island. The small settlement of New Sweden, founded along the Delaware River in 1638, was taken over by the Dutch in 1655. By 1674, English forces had won the former Dutch colonies in the Anglo-Dutch Wars; the province of New Netherland was renamed New York. Many new immigrants, especially to the South, were indentured servants—some two-thirds of all Virginia immigrants between 1630 and 1680.[30] By the turn of the century, African slaves were becoming the primary source of bonded labor. With the 1729 division of the Carolinas and the 1732 colonization of Georgia, the thirteen British colonies that would become the United States of America were established. All had active local and colonial governments with elections open to most free men, with a growing devotion to the ancient rights of Englishmen and a sense of self government that stimulated support for republicanism. All had legalized the African slave trade. With high birth rates, low death rates, and steady immigration, the colonies doubled in population every twenty-five years. The Christian revivalist movement of the 1730s and 1740s known as the Great Awakening fueled interest in both religion and religious liberty. In the French and Indian War, British forces seized Canada from the French, but the francophone population remained politically isolated from the southern colonies. By 1770, those thirteen colonies had an increasingly Anglicized population of three million, approximately half that of Britain. Though subject to British taxation, they were given no representation in the Parliament of Great Britain. Independence and expansion Main articles: American Revolution, American Revolutionary War, and Manifest Destiny Declaration of Independence, by John Trumbull, 1817–18 Tensions between American colonials and the British during the revolutionary period of the 1760s and early 1770s led to the American Revolutionary War, fought from 1775 through 1781. On June 14, 1775, the Continental Congress, convening in Philadelphia, established a Continental Army under the command of George Washington. Proclaiming that "all men are created equal" and endowed with "certain unalienable Rights," the Congress adopted the Declaration of Independence on July 4, 1776. The Declaration, drafted largely by Thomas Jefferson, pronounced the colonies sovereign "states." In 1777, the Articles of Confederation were adopted, uniting the states under a weak federal government that operated until 1788. Some 70,000–80,000 loyalists to the British Crown fled the rebellious states, many to Nova Scotia and the new British holdings in Canada.[31] Native Americans, with divided allegiances, fought on both sides of the war's western front. After the defeat of the British army by American forces who were assisted by the French, Great Britain recognized the sovereignty of the thirteen states in 1783. A constitutional convention was organized in 1787 by those who wished to establish a strong national government with power over the states. By June 1788, nine states had ratified the United States Constitution, sufficient to establish the new government; the republic's first Senate, House of Representatives, and president—George Washington—took office in 1789. New York City was the federal capital for a year, before the government relocated to Philadelphia. In 1791, the states ratified the Bill of Rights, ten amendments to the Constitution forbidding federal restriction of personal freedoms and guaranteeing a range of legal protections. Attitudes toward slavery were shifting; a clause in the Constitution protected the African slave trade only until 1808. The Northern states abolished slavery between 1780 and 1804, leaving the slave states of the South as defenders of the "peculiar institution." In 1800, the federal government moved to the newly founded Washington, D.C. The Second Great Awakening made evangelicalism a force behind various social reform movements. Territorial acquisitions by date Americans' eagerness to expand westward began a cycle of Indian Wars that stretched to the end of the nineteenth century, as Native Americans were stripped of their land. The Louisiana Purchase of French-claimed territory under President Thomas Jefferson in 1803 virtually doubled the nation's size. The War of 1812, declared against Britain over various grievances and fought to a draw, strengthened American nationalism. A series of U.S. military incursions into Florida led Spain to cede it and other Gulf Coast territory in 1819. The country annexed the Republic of Texas in 1845. The concept of Manifest Destiny was popularized during this time.[32] The 1846 Oregon Treaty with Britain led to U.S. control of the present-day American Northwest. The U.S. victory in the Mexican-American War resulted in the 1848 cession of California and much of the present-day American Southwest. The California Gold Rush of 1848–49 further spurred western migration. New railways made relocation much less arduous for settlers and increased conflicts with Native Americans. Over a half-century, up to 40 million American bison, commonly called buffalo, were slaughtered for skins and meat and to ease the railways' spread. The loss of the bison, a primary economic resource for the plains Indians, was an existential blow to many native cultures. Civil War and industrialization Main articles: American Civil War, Reconstruction, and Spanish-American War Battle of Gettysburg, lithograph by Currier & Ives, ca. 1863 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,[33] made them citizens, and gave them voting rights. The war and its resolution led to a substantial increase in federal power.[34] Immigrants landing at Ellis Island, New York, 1902 After the war, the assassination of President Lincoln radicalized Republican Reconstruction policies aimed at reintegrating and rebuilding the Southern states while ensuring the rights of the newly freed slaves. The resolution of the disputed 1876 presidential election 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.[35] 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 Main articles: American Expeditionary Force, Great Depression, and Military history of the United States during World War II An abandoned farm in South Dakota during the Dust Bowl, 1936 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.[36] 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.[37] In 1920, the women's rights movement won passage of a constitutional amendment granting women's suffrage. Partly because of 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,[38] 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 because of the war.[39] 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.[40] 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.[41] Superpower Main articles: Cold War, African-American Civil Rights Movement (1955–1968), and War on Terrorism Martin Luther King, Jr. delivering his "I Have a Dream" speech, 1963 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. Both the United States and the Soviet Union supported dictatorships, 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.[42] 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. President Ronald Reagan (1981–89) challenges Soviet general secretary Mikhail Gorbachev to tear down the Berlin Wall, 1987 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 Vice President 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.[43] 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.[44] In 1998, Clinton was impeached by the House on charges relating to a civil lawsuit and a sexual scandal, but he 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, al-Qaeda 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 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 or an explicit United Nations mandate for military intervention, Bush formed a Coalition of the Willing, and the U.S. invaded Iraq in 2003, removing President Saddam Hussein