1492. Spanish explorer Christopher Columbus lands in the Caribbean and initiates the era of European colonization.
1565. The first permanent European settlement was established at St. Augustine, Florida, by the Spanish.
1607. The British establish their first permanent settlement at Jamestown in present-day Virginia.
1611. First tobacco harvests in Virginia.
1619. First Thanksgiving is celebrated. The first slaves arrive in Jamestown.
1775-1783. Revolutionary War. The United States becomes independent from Great Britain.
1787. The Constitution is adopted and the present system of government put in place.
1789. George Washington becomes the first president of the United States.
1790. Samuel Slater establishes the first textile factory in Pawtucket, Rhode Island.
1794. The Post Office is established. Eli Whitney invents the cotton gin which spurs the expansion of the cotton industry.
1797. Eli Whitney develops interchangeable parts. This dramatically speeds up production and makes it easier to replace parts.
1803. The United States purchases the Louisiana Territory for $15 million, tripling the size of the nation.
1817. Work on the Erie Canal is begun. When it is completed the canal stretches 363 miles and joins the Hudson River to Lake Eire.
1846-1848. The United States fights the Mexican-American War and gains the territory that will become Arizona, California, Nevada, New Mexico, Utah, and parts of Colorado and Wyoming.
1849. Gold is discovered at Sutter's Mill in California, initiating a gold rush and mass migration to the West.
1859. The oil well is used for the first time and an oil boom is initiated in Pennsylvania.
1861-1865. American Civil War. In 1862, President Abraham Lincoln issues the Emancipation Proclamation which frees the slaves in the Confederate states.
1867. Barbed wire is invented. This makes it easier for Americans to settle the West. The United States purchases Alaska from Russia for $7.2 million.
1869. The transcontinental railroad is completed.
1898. The Spanish-American War ends with a U.S. victory and the nation acquires the Philippines, Guam, and Puerto Rico.
1901. The Open Door Policy is established to guarantee American companies the right to trade in China.
1913. The Sixteenth Amendment establishes the income tax.
1917-1918. The United States becomes involved in World War I.
1919. In separate constitutional amendments, women are given the right to vote and prohibition is established, making alcohol illegal in the United States.
1929. The New York Stock Exchange crashes and falls to its lowest level. The Great Depression begins.
1941-1945. The United States fights in World War II. The war ends when the United States drops the first atomic bombs on Hiroshima and Nagasaki, Japan. The United States helps establish the United Nations. The Cold War begins between the United States and its allies and the Soviet Union and its allies.
1951. The first commercial computer, UNIVAC, is sold to the U.S. Census Bureau.
1963-1973. American forces fight in Vietnam.
1965. The United States and Canada sign the Auto Pact.
1970s. The United States undergoes its worst economic recession since the Great Depression, partially as the result of oil crises in 1972 and 1979.
1989. US-Canada Free Trade Agreement goes into effect.
1992. The Cold War is officially declared to be over. The nation begins the second-longest period of economic expansion in its history.
1994. The United States, Canada, and Mexico establish the North American Free Trade Agreement (NAFTA).
2001. Terrorist attacks on New York's World Trade Center and the Pentagon on September 11 draw the United States into a military conflict with Taliban forces in Afghanistan.