An audience goes to the cinema for the first time, streetcars come to San Francisco, The Beatles' "White Album" goes to No. 1, and the first American test-tube baby is born, all on this day.
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Library of Congress
1973: The Endangered Species Act is signed into law by U.S. President Richard Nixon. The law was designed to protect critically imperiled species from extinction as a "consequence of economic growth and development untempered by adequate concern and conservation."