The more formally structured National League was founded in 1876. As the oldest surviving major league, the National League is sometimes referred to as the "senior circuit".[25] Several other major leagues formed and failed. In 1884, African American Moses Walker (and, briefly, his brother Welday) played in one of these, the American Association.[26] An injury ended Walker's major league career, and by the early 1890s, a gentlemen's agreement in the form of the baseball color line effectively barred black players from the white-owned professional leagues, major and minor.[27] Professional Negro leagues formed, but quickly folded. Several independent African American teams succeeded as barnstormers.[28] Also in 1884, overhand pitching was legalized.[29] In 1887, softball, under the name of indoor baseball or indoor-outdoor, was invented as a winter version of the parent game.[30] Virtually all of the modern baseball rules were in place by 1893; the last major change—counting foul balls as strikes—was instituted in 1901.[29] The National League's first successful counterpart, the American League, which evolved from the minor Western League, was established that year.[31] The two leagues, each with eight teams, were rivals that fought for the best players, often disregarding each other's contracts and engaging in bitter legal disputes.[32]
The New York Giants baseball team, 1913. Fred Merkle, sixth in line, committed a baserunning gaffe in a crucial 1908 game that became famous as Merkle's Boner.
A modicum of peace was eventually established, leading to the National Agreement of 1903. The pact formalized relations both between the two major leagues and between them and the National Association of Professional Base Ball Leagues, representing most of the country's minor professional leagues.[33] The World Series, pitting the two