National Association of Professional Base Ball Players (U.S.)

"The National Association of Professional Base Ball Players (NAPBBP), often known simply as the National Association (NA), was the first fully-professional sports league in baseball. The NA was founded in 1871 and continued through the 1875 season. It succeeded and incorporated several professional clubs from the previous National Association of Base Ball Players (NABBP) of 1857–1870, sometimes called "the amateur Association". In turn, several NA clubs created the succeeding National League of Professional Baseball Clubs (the National League, founded 1876), which joined with the American League of Professional Base Ball Clubs (the American League, founded 1901) to form Major League Baseball (MLB) in 1903."--Wikipedia, 2020