Considered by many to be the founder of modern baseball. Games similar to baseball had been played throughout the early 19th century in the United States, but mostly as unorganized children's games such as rounders. In 1845, Cartwright formed the Knickerbocker Base Ball Club of New York, and decided to draw a formal set of rules. The following year, the Knickerbockers played the first organized baseball game at the Elysian Fields in Hoboken, NJ, losing 23-1 to the New York Base Ball Club. The most significant changes Cartwright made from the informal game were to:
- Set the distance between the bases, and set the number of bases at 4
- Eliminate the rule that a runner was out if hit by a thrown ball
- Suggest a fixed number of outs for each team's turn at bat
- Separate the field of play into fair (in play) and foul (out of play).
In 1849, Cartwright left New York and the Knicks for California, seeking gold. He reportedly taught "the New York game" of baseball to everyone he met along the way who was willing to play. After a brief stay in California, he left for Honolulu, Hawaii, where he lived until his death in 1892. While in Hawaii, Cartwright continued to teach baseball, but also founded Honolulu's fire department and at one time was a financial advisor to the Hawaiian royal family.
For most of the early 20th century, the accepted belief was that Abner Doubleday, not Alexander Cartwright, had invented baseball, teaching troops the game in Cooperstown, NY. While Cooperstown makes a more picturesque home for the Baseball Hall of Fame than Hoboken, the game Doubleday played was probably no different than the popular children's games. But Cartwright's departure from the East Coast and the demise of the Knickerbockers soon thereafter kept his innovations hidden until 1938, when a committee formed by the Hall of Fame reviewed Cartwright's journals. He was then inducted into the Hall of Fame, and in 1947 a New York librarian named Robert Henderson published Bat, Ball and Bishop describing Cartwright's contributions to baseball. | 
