alternatehistory.com

Actually, Boston did have an American League baseball team for a couple of years, to go along with the Braves. Ban Johnson thought that his new league had to enter the Boston market, and put the Boston Americans there.

However, what the American League really wanted was a team in New York, but was blocked from the Giants. In 1903, the other National League owners forced the Giants to relent, and the Americans relocated to New York.

However, originally it was supposed to be the Baltimore Orioles who were to move to New York. Its unclear why the Boston Americans moved instead, but a change of ownership seems to have been the deciding factor.

One thing that is clear is that the New York team wouldn't have been called the "Yankees", which was a moniker adopted by New York sportswriters due to their New England origin. But what would have been the other effects? Could Boston have supported two major league teams? Would Baltimore have eventually gotten a replacement team?
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