On this date in history:
In 1896, the U.S. Supreme Court handed down the Plessy vs. Ferguson decision that determined "separate but equal" racial policies are constitutional.
In 1917, President Wilson signed the Selective Service Act of 1917 by which the United States raised an army for service in Europe during World War I.
In 1933, the U.S. Congress created the Tennessee Valley Authority for flood control and rural electrification.
In 1944, Allied troops captured Monte Cassino in Italy after one of the longest and bloodiest battles of World War II.
In 1969, Apollo 10 blasted off into space to perform a test run of what would become the Apollo 11 moon landing, coming to within 51,200 feet of the moon's surface. The mission also sent back the first televised color images of earth.
In 1979, a U.S. court jury in Oklahoma City awarded $10.5 million to the estate of Karen Silkwood, a laboratory technician contaminated by radiation at a Kerr-McGee plutonium plant in 1974.
In 1980, Mount St. Helens in southwestern Washington state erupted, blowing the top off the mountain and killing 57 people.
In 1990, East and West Germany signed a treaty for economic, monetary and social union. West German Chancellor Helmut Kohl said the pact marked the "birth of a free and unified Germany."
In 1991, chemist Helen Sharman became the first Briton in space when she blasted off from the Baikonur Cosmodrome aboard a Soviet spacecraft.
In 1992, bandleader Lawrence Welk, whose bubbly champagne dance music brought him wide popularity, died at age 89.
In 2004, Randy Johnson, Arizona's 40-year-old left-hander, pitched a perfect game in a 2-0 win over Atlanta. He was the oldest major league pitcher to accomplish the feat.
In 2018, 10 people -- eight students and two teachers -- died after a fellow student opened fire at Santa Fe High School, near Houston.