Powderpuff refers to an annual tradition at many high schools and colleges where women don men's football gear and play football.
Women were playing football on Western's campus as early as 1931, according to the research conducted by the library.
Wikipedia has the following description of the first Powderpuff Football game in the US:
The first Powderpuff Football game was played on October 20, 1945, at Eastern State Teachers College, in Madison, South Dakota. Eastern had canceled many campus activities for the duration of World War II. Among these were the annual homecoming celebration and intercollegiate sports, including football. With the signing of the Peace Treaty with Japan on September 2, 1945, and the war’s official end, Homecoming was again on the schedule at Eastern. The traditional football game seemed out of the question, however, due to the wartime military draft. Just three men enrolled for the fall term that year. - Wikipedia
Photographs show Western State College women playing football on campus in 1931.
Cathy Wilkens, an archives volunteer at the Savage Library, says "We think this pretty well documents the fact that Western State College was playing Powderpuff football long before Eastern State Teachers College in North Dakota claims to have played the first game in 1945."
A quote published in the 1940 edition of Western's yearbook, the Curecanti (above), includes the following description:
Women's coeds shelved their femininity for a day before the varsity took the spotlight at Homecoming, and tackled that sport of the man's world--football. The game, played before the camera of Lee Orr, Fox-Movietone photographer, gained nation-wide publicity for the fragile feminine footballers through an Associated Press release for the story.