Alexander Cartwright is Officially Credited by the United States Congress with Inventing the Modern Game of Baseball

In the early twentieth century, the invention of baseball was attributed to Abner Doubleday, widely considered a myth by later sports historians.

Cartwright was a bookseller in Manhattan, and a volunteer fireman. Cartwright founded the Knickerbocker Base Ball Club (after the Knickerbocker Fire Engine Company) in 1842. They played a brand of stick-and-ball game called the town game. In 1845 Cartwright and a committee from his club drew up rules converting this playground game into a more elaborate and interesting sport to be played by adults. He and other firemen played on a field at 47th and 27th Streets. The rules of the modern game are based on their by-laws, and Cartwright is thought to be the first person to draw a diagram of a diamond shaped field.
The Knickerbockers participated in the first competitive game (as opposed to intramural) under these rules on June 19, 1846. The Knickerbockers lost 21–1 to the New York Nine.

Alexander Joy Cartwright (1820-1892) of New York invented the modern baseball field in 1845. Alexander Cartwright and the members of his New York Knickerbocker Base Ball Club, devised the first rules and regulations for the modern game of baseball.