Combing though old copies of Sports Illustrated, I was surprised to find women on a what seemed like a decent amount of covers of the 1950s. That is, a good amount for the 1950s. When I looked into it more I discovered that in S.I.'s first decade of existence (1954-1965), female athletes were featured on 74 covers (12.6% of the total). Before you react to that number, know that in the past decade (2000-2011) women only appeared on 35 Sports Illustrated covers (4.9%)—and only 18 times (2.5%) as the primary or sole image [source].
All of a sudden the 1950s are feeling mighty progressive. And with much more appealing art direction.