This is a container category. Due to its scope, it should contain only subcategories.

Here there are categories for teams in the National Association of Professional Base Ball Players ("National Association" or "NA", 1871–1875). All their players are commonly considered "major leaguers" although Major League Baseball does not recognize the NA as a major league. There is a convenient subcategory(*) for those 1871–1875 teams.

Six of the NA clubs founded the National League in 1876 with two newcomers. Three of the six (based in Boston, Philadelphia, and St. Louis) are represented by two overlapping categories for their players before and after 1875/76; three are represented by one category spanning 1875/76 (Chicago, Hartford, and New York).