After beginning the 1890 season with Detroit, Campau returned to the major leagues with the St. Louis Browns of the American Association. He appeared in 75 games for the Browns, all but one in the outfield. Campau led the league with nine home runs and was among the league leaders with a .513 slugging percentage (2nd), .322 batting average (9th), 12 triples (8th), and 75 RBIs (9th). He also stole 36 bases, contributing to his having the best sabermetric power-speed number in the league. During the month of July, Campau established a major league record (still intact) with 15 consecutive multi-hit games.