1513 Spanish explorer Juan Ponce de Leon sights Florida.
1964 The Good Friday Earthquake, the strongest known earthquake in American History, measuring 8.4 on the Richter scale, hits Alaska, killing some 130 people.
Five-story J.C. Penney Building, 5th Avenue and Downing Street, Anchorage, Alaska, partly collapsed by the March 28, 1964 earthquake. Note undamaged buildings nearby.
1800 The frigate USS Essex became the first American warship to round Africa's Cape of Good Hope, as it sailed on a mission to escort merchant ships returning from the Dutch East Indies.
1979 America gets a scare when the Three Mile Island nuclear power plant in Pennsylvania malfunctions; thousands flee, but no one is injured.
1848 An ice jam at the source of the Niagara River causes Niagara Falls to stop flowing for the first time in recorded history.
1943 The U.S. government began requiring Americans to ration fat, meat, and cheese as part of a massive national program to help win World War II.
1867 Secretary of State William H. Seward signs an agreement to purchase Alaska from Russia for $7.2 million, about two cents an acre.
1981 President Reagan is shot and seriously wounded by John W. Hinckley Jr. outside a Washington, D.C. hotel.
1933 Congress establishes the Civilian Conservation Corps to help put men to work during the Depression.
1970 Explorer I, the first U.S. Satellite, reenters the atmosphere after twelve years in orbit.
1865 Union troops win a victory at the Battle of Five Forks, Virginia, causing Robert E. Lee to tell Jefferson Davis that Petersburg and Richmond must be evacuated.
1996 Fast food chain Taco Bell announces it has bought the Liberty Bell and renamed it the Taco Liberty Bell, and thousands believe the April Fool's Day prank.
1917 Woodrow Wilson calls for a declaration of war against Germany, saying, "The world must be made safe for democracy."
1953 The journal Nature publishes a paper by British scientist Francis Crick and American scientist James Watson, describing a double helix structure for DNA.