1915 witnessed the tightest pennant race in Major League history, as three teams (Chicago, St. Louis and Pittsburgh) fought into the last weekend of the season. On the season's final day, Sunday, October 3, Chicago split a doubleheader with Pittsburgh, winning the darkness-shortened seven-inning nightcap, 3-0; this combined with St. Louis' 6-2 win over Kansas City, knocked Pittsburgh back to third (albeit just a half-game behind), with Chicago and St. Louis in a virtual tie for first. But since the Whales (86-66) played two fewer games than the St. Louis Terriers (87-67), they were awarded the pennant based on their slightly better winning percentage (.566 to .565). Pittsburgh, with one game unplayed, ended up at 86-67 (.562).
After the 1915 season the owners of the American and National Leagues bought out half of the owners (Pittsburgh, Newark, Buffalo, and Brooklyn) of the Federal League teams. Two Federal League owners were allowed to buy struggling franchises in the established leagues: Phil Ball, owner of the St. Louis Terriers, was allowed to buy the St. Louis Browns of the AL, and Charles Weeghman, owner of the Chicago Whales, bought the Chicago Cubs. Both owners merged their teams into the established ones. The Kansas City franchise had been declared bankrupt and taken over by the league office after the close of the regular season, and the Baltimore owners rejected the offer made to them. They had sought to buy and move an existing franchise to their city, but were rebuffed, and sued unsuccessfully.