April 2, 1513 - Spanish explorer Ponce De Leon sighted Florida and claimed it for the Spanish Crown after landing at the site of present day St. Augustine, now the oldest city in the continental U.S.
April 3, 1860 - In the American West, the Pony Express service began as the first rider departed St. Joseph, Missouri. For $5 an ounce, letters were delivered 2,000 miles to California within ten days. The famed Pony Express riders each rode from 75 to 100 miles before handing the letters off to the next rider. A total of 190 way stations were located about 15 miles apart. The service lasted less than two years, ending upon the completion of the overland telegraph.
April 6, 1896 - After a break of 1500 years, the first Olympics of the modern era was held in Athens, Greece.
April 15, 1912 - In the icy waters off Newfoundland, the luxury liner Titanic with 2,224 persons on board sank at 2:27 a.m. after striking an iceberg just before midnight. Over 1,500 persons drowned while 700 were rescued by the liner Carpathia which arrived about two hours after Titanic went down.
April 18, 1775 - The Midnight Ride of Paul Revere and William Dawes occurred as the two men rode out of Boston about 10 p.m. to warn patriots at Lexington and Concord of the approaching British.
April 24, 1800 - The Library of Congress was established in Washington, D.C. It is America's oldest federal cultural institution and the world's largest library. Among the 145 million items in its collections are more than 33 million books, 3 million recordings, 12.5 million photographs, 5.3 million maps, 6 million pieces of sheet music and 63 million manuscripts. About 10,000 new items are added each day.
April 30, 1789 – George Washington became the first U.S. President as he was administered the oath of office on the balcony of Federal Hall at the corner of Wall and Broad Streets in New York City.