The United States, with its large size and geographic variety, includes most climate types. To the east of the 100th meridian, the climate ranges from humid continental in the north to humid subtropical in the south. The Great Plains west of the 100th meridian are semi-arid. Much of the Western mountains have an alpine climate. The climate is arid in the Great Basin, desert in the Southwest, Mediterranean in coastal California, and oceanic in coastal Oregon and Washington and southern Alaska. Most of Alaska is subarctic or polar. Hawaii and the southern tip of Florida are tropical, as well as its territories in the Caribbean and the Pacific. States bordering the Gulf of Mexico are prone to hurricanes, and most of the world's tornadoes occur in the country, mainly in Tornado Alley areas in the Midwest and South. Overall, the United States has the world's most violent weather, receiving more high-impact extreme weather incidents than any other country in the world.
The Rocky Mountains, west of the Great Plains, extend north to south across the country, peaking around 14,000 feet (4,300 m) in Colorado. Farther west are the rocky Great Basin and deserts such as the Chihuahua and Mojave. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast, both ranges reaching altitudes higher than 14,000 feet (4,300 m). The lowest and highest points in the contiguous United States are in the state of California, and only about 84 miles (135 km) apart. At an elevation of 20,310 feet (6,190.5 m), Alaska's Denali is the highest peak in the country and in North America. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands, and Hawaii consists of volcanic islands. The supervolcano underlying Yellowstone National Park in the Rockies is the continent's largest volcanic feature.
More InfoEstimating the native population of North America at the time of European contact is difficult. Douglas H. Ubelaker of the Smithsonian Institution estimated that there was a population of 92,916 in the south Atlantic states and a population of 473,616 in the Gulf states, but most academics regard this figure as too low. Anthropologist Henry F. Dobyns believed the populations were much higher, suggesting 1,100,000 along the shores of the gulf of Mexico, 2,211,000 people living between Florida and Massachusetts, 5,250,000 in the Mississippi Valley and tributaries and 697,000 people in the Florida peninsula.
More InfoWith the advancement of European colonization in North America, the Native Americans were often conquered and displaced. The first Europeans to arrive in the contiguous United States were Spanish conquistadors such as Juan Ponce de León, who made his first visit to Florida in 1513. Even earlier, Christopher Columbus landed in Puerto Rico on his 1493 voyage. The Spanish set up the first settlements in Florida and New Mexico such as Saint Augustine and Santa Fe. The French established their own as well along the Mississippi River. Successful English settlement on the eastern coast of North America began with the Virginia Colony in 1607 at Jamestown and with the Pilgrims' Plymouth Colony in 1620. Many settlers were dissenting Christian groups who came seeking religious freedom. The continent's first elected legislative assembly, Virginia's House of Burgesses, was created in 1619. The Mayflower Compact, signed by the Pilgrims before disembarking, and the Fundamental Orders of Connecticut, established precedents for the pattern of representative self-government and constitutionalism that would develop throughout the American colonies.
More InfoThe United States played a leading role in the Bretton Woods and Yalta conferences with the United Kingdom, the Soviet Union, and other Allies, which signed agreements on new international financial institutions and Europe's postwar reorganization. As an Allied victory was won in Europe, a 1945 international conference held in San Francisco produced the United Nations Charter, which became active after the war. The United States and Japan then fought each other in the largest naval battle in history, the Battle of Leyte Gulf. The United States worked on a secret project, known as the Manhattan Project. They eventually developed the first nuclear weapons, and tested them in the Jornada del Muerto desert about 35 miles (56 km) southeast of Socorro, New Mexico. This was known as the Trinity Test. The test was successful, which eventually led to the bombing of Japanese cities Hiroshima and Nagasaki; the Japanese surrendered on September 2, ending World War II.
More InfoFollowing the decisive Franco-American victory at Yorktown in 1781, Britain signed the peace treaty of 1783, and American sovereignty was internationally recognized and the country was granted all lands east of the Mississippi River. Nationalists led the Philadelphia Convention of 1787 in writing the United States Constitution, ratified in state conventions in 1788. The federal government was reorganized into three branches, on the principle of creating salutary checks and balances, in 1789. George Washington, who had led the Continental Army to victory, was the first president elected under the new constitution. The Bill of Rights, forbidding federal restriction of personal freedoms and guaranteeing a range of legal protections, was adopted in 1791.
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