The first and earliest written evidence of baseball in America is a bylaw written in 1791 in Pittsfield, Massachusetts. The document, discovered by Society for Baseball Research member John Thorn in 2004, offers strong evidence that baseball is a unique American game, and it casts doubt on the long held belief that baseball was derived from rounders, a British game. It also raises the question of the origins of cricket, as it has been widely thought that baseball followed cricket, which was developed from a folk game known as stool ball (1085 A.D).

As far back as 2000 B.C. ball and stick type games have been played. Hieroglyphics depict ancient Egyptians playing a game similar to baseball in 1500 B.C., although there exists some major differences between its depiction and the modern game.

The 1791 Massachusetts by-law banned the playing of the game within 80 yards of the town meeting house. The first documented formal organization to play baseball in America was the NY Knickerbockers established on September 23, 1845. The first rules were written by Alexander Cartwright, considered to be the Father of modern baseball. However, long before this time ball playing of one sort or another was noted by many authors and in many documents.

A May 8, 1844 city Ordinance in New York City prohibits "ball" playing of any sort. Abner Doubleday was said to have "invented" the game of baseball in 1839, although a later inquiry proved this to be a myth. Cartwrights role in baseball has also been questioned. Most experts and historians now agree that he was simply the first to write down the rules that had existed for quite some time. In addition, there is strong evidence that rule changes were one of the reasons Cartwright wrote them down.

There has been a lot written about the sport after the founding of the Knickerbockers, such as articles about the popularity and evolvement of the "New York Game" rules into the mainstream of baseball. The original Knickerbocker rules addressed foul lines and deleted the "plug out," which involved hitting the runner with the ball to gain an out. They also delineated the tag-out and the force-out. Strangely, they dont provide a pitching distance or a baseline length. Forty-two paces was the actual written distance from home to second base, and from first to third. "Innings" were also not mentioned. Instead, the first team to twenty-one was declared the winner, given both teams are allowed an equal number of at-bats. The pitching method was also described as underhand, perhaps similar to town ball, another early game with English roots.

The rules may have first been written by Cartwright, but there is a long and involved history of earlier games with similar rules. Many American and opposing English claims of inventing baseball have tried to argue their positions by presenting evidence to back their claims. Despite all of this, the origin of modern baseball still remains a mystery.

After 1845, the history of baseball in America starts to be fairly clear. The rules were standardized in 1857. In 1858, the first baseball league, the National Association of Base Ball Players (NABBP), emerged. They were not considered professional players, as they received no money for their participation. However, the games were public and admission was charged to witness the games. The first documented college baseball game was played in 1859 as Amherst defeated Williams 73-32 in 26 innings in Pittsfield, Massachusetts.

In 1860, the "New York Game" was commonly referred to as "the National pastime" in many written works. Baseball gained momentum in popularity and slowly spread throughout the Country during the Civil War. Over 100 clubs were in existence when the war ended and in 1869, the world's first professional baseball team was established. The Cincinnati Red Stockings ended their first season undefeated. The NABBP split into two groups, one for the amateurs and one for the professionals. The amateur leg of the association dissolved after only a few years.

The National League, which still exists, was established in 1875 after the NABBP proved ineffective on several levels. The power shifted to the club organizations and baseball entered into an age full of conflict, remembered mostly for the dreaded player reserve clause that oppressed players and held them as "slaves" to their contracts.

Blacks and Hispanics or any other non-white players were repeatedly forced out, left out, or sent to the minor leagues. This was a shameful practice that didnt end until 1947. The Western League of Baseball Players, a minor league of the Great Lakes States area became the American League in 1899. A new era in baseball began in 1901. It was known as the "Dead Ball Era", because of a sharp decrease in offense produced in both leagues. This era continued until the emergence of Babe Ruth in 1919.