On June 19, 1846 - though the date is often celebrated on May 23, when the first formal rules were used in practice - a group of young men in Hoboken, New Jersey, played what's often called the first organized baseball game under modern rules. The field was a grassy spot called Elysian Fields, just across the Hudson River from Manhattan. The teams were the New York Nine and the Knickerbocker Base Ball Club. The Knickerbockers had written down the rules. The New York Nine clobbered them 23 to 1.
The rules were the work of a bank clerk named Alexander Cartwright. He had decided that bases would be 90 feet apart, that there would be three outs per inning, and that runners couldn't be tagged out by being hit with a thrown ball - which had been a popular and painful way to play before. These ideas seem simple now, but they basically invented the sport. Earlier versions of bat-and-ball games, like rounders and town ball, had been around for centuries, especially in England. Cartwright's version turned them into something new.
From that game, baseball spread fast. Soldiers in the Civil War played it in their camps and carried the game home to every corner of the country. The first professional team, the Cincinnati Red Stockings, came along in 1869. Today Major League Baseball has 30 teams, and stadiums fill with peanuts, popcorn, and the crack of bats from spring through fall. Cartwright's quiet day at Elysian Fields, with a homemade rulebook and a lopsided score, was the moment when America's pastime began.