The Foundation of Modern Baseball
Major League Baseball as we know it today was created in 1903 when the American League and National League officially recognized each other as equal major leagues. Before this, the two leagues competed fiercely and did not play each other. The peace agreement between them established the structure of professional baseball that continues today.
The National League (1876)
The National League was the first professional baseball league, founded in 1876. It was created to organize baseball teams and establish rules for competition. The league started with eight teams and focused on making baseball a respected sport. Many teams from this era, like the Chicago Cubs and Atlanta Braves, still exist today.
The American League (1901)
The American League was founded in 1901 as a rival to the established National League. It quickly gained popularity and challenged the National League's authority over professional baseball. This competition between the leagues lasted only two years before they agreed to work together.
The 1903 World Series Agreement
The turning point came in 1903 when the two leagues agreed to have their champions play each other in what became the World Series. The Boston Americans defeated the Pittsburgh Nationals in the first modern World Series. This agreement brought stability to professional baseball and established MLB as the sport's highest level.
Early MLB Structure
After 1903, MLB consisted of the American League and National League, each with multiple teams. The leagues operated somewhat independently but recognized each other's authority. This basic structure has remained similar for over 120 years, though the number of teams and divisions has changed. 
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