The American League moves from minor-league status to the majors, with the existing Washington Senators, (the 1900 AL’s Kansas City Blues were relocated to the nation’s capital) Cleveland Lake Shores (renaming themselves the Blues), Detroit Tigers, Milwaukee Brewers and Chicago White Sox joined by new additions the Baltimore Orioles (who had sat out a season after being booted from the National League in 1899), and the expansion Philadelphia A’s (created to compete against the NL’s Phillies) and Boston Americans (created to compete with the NL’s Boston Braves). Three clubs are cut from the AL: The Indianapolis Hoosiers, who joined the Western Association; the Buffalo Bisons, who joined the Eastern League; and the Minneapolis Millers, who joined the Western League.
All eight original AL teams still exist, seven contiguously. The White Sox and Tigers still completely intact, with no changes. Four clubs changes cities and/or nicknames: The Blues are now the Guardians, the Senators became the Minnesota Twins, the A’s are now in Oakland, and the Americans became the Red Sox. The Orioles have a more complicated history, by almost immediately moving to St. Louis to become the Browns, but returning to Baltimore in 1954 and reverting to the Orioles nickname.
The last team, Milwaukee, exists in 2023, but not as the same franchise as 1901. The Brewers are now in the National League, but this Brewers team were born in Seattle in 1969 as the Pilots and were moved to Milwaukee in in 1970.
The league played a 140-game schedule in 1901, and with roster limits set at 14, commenced a raid on National League talent. The AL also (temporarily) did away with the reserve clause, setting a five-year limit on team ownership of a player.
The White Sox had won the first American League pennant in 1900, with the AL still consider a minor league. They would finish first in the AL in 1901 as well, with an 83-53-1 record. Both of those pennants ended the White Sox seasons, however, as there was no World Series in those years.