Women have been playing professional baseball since the early 1930s, when Chattanooga Lookouts pitcher Jackie Mitchell struck out Babe Ruth and Lou Gehrig in succession, during an exhibition game against the New York Yankees in 1931.
The AAGPBL was a league that began to operate in 1943 in cities located on or near Lake Michigan. The main promoter was Philip K. Wrigley, owner of the Chicago Cubs, who worried about the viability of male professional baseball players during World War II decided to establlish an alternate attraction. The league folded after the end of the 1954 season. Over the years the rules, equipment, and style of play in the league changed from softball to baseball (e.g., the size of the ball at the beginning was 12" in circumference, but at the end it was 9 1⁄4"). Eleven girls from Manitoba played in the league, including Callow. All of them received honorary inductions into the National Baseball Hall of Fame and Museum (1988), the Canadian Baseball Hall of Fame (1998), and the Manitoba Softball Hall of Fame (1998).
During her career, Callow was among the most feared sluggers of the AAGPBL. A four-time All-Star, she was the Babe Ruth equivalent of the AAGPBL, accumulating more home runs and triples than any other player in league history. A rare combination of power, speed, patience at the plate and fielding in a multiskilled package, she also overwhelm opposite teams with her speed, by drawing walks, stealing bases, and catching difficult fly balls.
Callow entered the AAGPBL in 1947 with the Peoria Redwings, playing for them during her rookie season before joining the Chicago Colleens expansion team for a small time in 1948. She was traded to the Rockford Peaches during the midseason and remained with them for the rest of her career, including in three consecutive championship titles (1948-'50) and also in the team's last ever game in 1954.
Beginning in 1948, Callow led the league in triples for four straight years and ended up with 60 in her career. She started off slow in the home run category with none during her rookie season, but by the rest of her eight years career she belted 55 to top the all-time list.
In 1948, Callow ended with a .251 batting average, but tied for second in home runs (6) and led for the first time the league in triples (15). She repeated as the leader in triples in 1949 (11) and 1950 (11). In 1951 she gained her first selection for the All-Star Team, after recording career-highs in average (.326), runs (66), runs batted in (84), hits (124), doubles (16), stolen bases (40), total bases (172) and walks (49); claimed her fourth triple title in a row, had the best fielding percentage of any outfielder, and tied with Fort Wayne Daisies' Betty Foss and teammate Alice Pollitt in home runs (4).
In 1952 Callow was unable to repeat the success of the previous season. Nevertheless, she finished third in home runs (8), fourth in triples (6), fifth in total bases (151), eight in runs (56), ninth in RBI (49), and still made the All-Star Team. But she rebounded in 1953, hitting .303 (3rd league-best) with eight home runs (2nd) and 58 RBI (7th). She also scored 58 runs (8th) and stole 37 bases (8th), while making the All-Star Team for the third time.
By the time of her last season, Callow said goodbye in a really meaningful way by hitting .324 with 20 home runs, 58 RBI and 23 stolen bases in limited playing time. In addition, she joined Joanne Weaver as the only two AAGPBL players to reach the 20 home runs and 20 stolen bases plateaus in the same season. She is also one of five players to collect 400 or more career-RBI, ranking third (407) behind Dorothy Schroeder (431) and Inez Voyce (422), and over Elizabeth Mahon and Pepper Paire (400 each).In 1992, filmmaker Penny Marshall premiered her film A League of Their Own, which was a fictionalized account of activities in the All-American Girls Professional Baseball League. Starring Geena Davis, Tom Hanks, Madonna, Lori Petty and Rosie O'Donnell, this film brought a rejuvenated interest to the extinct AAGPBL. Many baseball historians consider the league's players as pioneers of an important movement which has eventually brought women's athletics to the prominent place it occupies in the 21st century.