Mount Union College's radio station was born January 10, 1966 by a group of Mount Union students. It started as a carrier current station using the College's power lines to reach the residence halls. The original station contained one studio in the basement of Miller Hall. WRMU continued as a campus-only station until October 17, 1970 when the Federal Communications Commission (FCC) granted the College a license for WRMU to become a full-fledged FM station with the frequency 91.1. During the 70's the station featured a mix of jazz, blues, classical and rock music. The station also began to broadcast Mount Union football and basketball games. From the basement of Miller Hall, the radio station moved to new quarters on the second floor of Memorial Hall in 1983. The station grew from two studios to a total of four. A year later in 1984, the station began broadcasting in stereo. In May 1996, the station moved into its new and current home in the Hoover-Price Campus Center, where visitors can watch air talent through windows in the on-air studio. Throughout the station's history Mount Union students have worked to provide the community and campus with the best programming possible. WRMU currently features jazz during the week and "oldies" during the weekend.
In January 2010, student-run radio shows broadcasting from 10pm to 2am on weekdays switched to the collective moniker of "R91", short for "Raider 91." The student shows feature a wide variety of music from rock to hip-hop, pop and alternative. R91 is meant to appeal to the Mount Union student body, in contrast to the daytime smooth jazz/oldies format that reaches out to the local Canton, Ohio area.