[Syd Thrift]

1961 is the next expansion. The Federal League pops up in 1914-1915 but that's all she wrote. Baseball's... weird, although it reflects the rest of the country's sports in this as well. Basically, 16 teams might have been too many for the game into the teens, then the league first became super popular in the 20s, then the Depression hit and frankly MLB did well to not contract (the Browns had a couple seasons where they drew like 80,000 fans for the entire year), then World War II came about with its own issues, then in the 50s the league, which had its 16 teams concentrated into 10 cities, started seeing its "double" teams move around - the Boston Braves moved to Milwaukee, the St. Louis Browns moved to Baltimore and became the Orioles, etc. - and finally in 1961 and 1962 the leagues expanded for basically the first time in modern history.

It could be worse! The NHL had six teams from the Great Depression to the late 60s. The NFL had more teams but a. also contracted a lot in the 30s, and b. was still seeing franchises fold into the 1950s. The NBA... well, basketball was not a particularly popular sport in the 40s and 50s and that's reflected by the fact that the teams were concentrated in the New York area and the Upper Midwest, with teams in places like Rochester, Syracuse, and Fort Wayne, Indiana well into the late 50s (I don't think the Syracuse Nationals moved to Philadelphia to become the 76ers until the early 60s in fact).