When the Western League launched its assault on the established National League in 1901, Boston was one of the key cities the new circuit — the American League — moved into, with the franchise now known as the Boston Red Sox.
Boston, first as the Americans from 1901-07 and then as the Red Sox, were one of the dominant clubs of the early 20th century, winning five World Series titles between 1903-18 to go with six AL pennants.
The first World Series championship was a stunner as it came in 1903, just the AL’s third season, and was the first meeting between American and National league champions, something that in 1905 became an annual tradition.