Radio transmissions at the university date to 1912, when a professor named F.W. Springer began experimenting with broadcasts, though he probably just used a spark gap transmitter. Activities were suspended by World War I, but electrical engineering professor C.M. Jansky, Jr. (the older brother of Karl Jansky) was doing broadcasting again by 1920. He had previously been at the University of Wisconsin, where he had helped at station 9XM (soon to be called WHA). Jansky used the call sign 9XI and provided reports on farm markets and weather. In February 1922, when a heavy snowstorm knocked out newswire services into the region, personnel at the Minneapolis Tribune convinced operators to help them retrieve the day's news through a roundabout series of amateur radio relays.

Focus on education

The University received the first AM license in the state on January 13, 1922 for the call sign WLB (the same day as Wisconsin's WHA), and programming was extended to include lectures, concerts, and football games. In the 1930s and 1940s, the station broadcast a considerable amount of educational material and was used for distance learning — a practice that continued into the 1990's. The call sign was changed to KUOM by 1945. The station had a paid staff, unlike a smaller campus-only station that emerged later.

A polio epidemic in 1946 that resulted in temporary school closings and the cancellation of the Minnesota State Fair led the station to create programming for children who where homebound. Those programs, along with others broadcast in the 1940s, were recognized for their importance and led to several awards being given to the station.

For nearly 70 years, WLB and later KUOM time-shared the already daytime-restricted 770 kHz frequency with WCAL of St. Olaf College in Northfield, Minnesota, so each station averaged just about six hours of programming each day. The University of Minnesota eventually made an agreement with St. Olaf where WCAL would get land for a powerful FM transmitter on U of M land near Rosemount, Minnesota in exchange for the shutdown of WCAL's AM transmitter so that KUOM could transmit exclusively on the frequency during the day. The agreement came to fruition in 1991.

Campus radio

Another station, WMMR (for "Women's and Men's Minnesota Radio"), was created on campus in 1948, with studios in Coffman Memorial Union. Focused on providing a service for the student body, it originally broadcast via carrier current on campus, using the frequency 730 AM (hence the oft-used tag-line "Radio 73"). Legend had it that the WMMR call sign was actually assigned to the station by the FCC, pre-dating the assignment of those same call letters to the well-known Philadelphia station WMMR. The legend continued that the FCC forgot that it had allowed carrier current stations to use a call sign, and gave away the sign to the Philly station. The Minnesota students stuck to their guns and never changed their call sign, and there were of course no legal repercussions given that carrier current stations do not actually go over the air. By the 1970's, this legend lived merely as a tale passed down from year to year in an oral tradition, and has never been documented enough to confirm.

The station's volunteer engineers famously talked themselves into the campus steam-tunnel system from time to time when they needed to maintain the cables that connected the station's studios to the small transmitters located in each of the dormitory buildings. Tales were told of singed eyebrows from coming too close to the hot steam pipes used to heat the buildings. Eventually the station added an FM signal to the Minneapolis cable television system.

This was an entirely student-run operation, relying on volunteers. By the mid-60's through the end of its life, the station tried to emulate the management structure of a typical AM rocker of the day, with an appointed General Manager, Program Director, Music Director, and other management positions. From time to time, somebody actually sold an advertising slot, but the station more or less maintained itself using a small stipend from the Speech Communications department. Even then, the volunteers managed to put out programming for nearly 18 hours a day most days of the school year, and taught many a student the ins and outs of how to operate a studio. A news and sports operation broadcast daily reports, and the basketball, football and hockey programs were usually broadcast with live play-by-play. A number of live broadcasts from the Whole Music Club and the Great Hall at the union also took place, and the station served to promote other campus events such as the "Campus Carny" held annually in the old field house.

Garrison Keillor, the well-known host of Minnesota Public Radio's A Prairie Home Companion, began his radio career broadcasting classical music on WMMR as a student in the early 1960s. He then worked at KUOM from 1963 to 1968.

Radio K

In the early 1990s, after a great deal of lobbying by WMMR General Manager Jim Musil — who also designed the prolific Radio K logo — the university began to examine the idea of merging WMMR and KUOM. The university explained the transition to a music format by saying that most of the educational value of KUOM had been superseded by other media outlets by this time. To avoid the lack of direction found at some college music stations, the new "Radio K" had a small full-time staff to oversee operations and provide a certain level of continuity, while students would provide much of the on-air talent while going through their radio studies. The transition finally took place in 1993, and the station started broadcasting as "Radio K" on October 1 that year.

Radio K has received accolades from local newspapers and magazines, especially the weekly City Pages which has consistently ranked the station among the best for music in the region. Pitchfork Media founder Ryan Schreiber also commonly cites the station's influence as having been an integral factor in his decision to start an online publication dedicated to the coverage of independent music. The station receives about 120 new recordings each month which are filtered through a large group of reviewers and disc jockeys. Recordings that pass muster are added to a large playlist that is constantly updated, and on-air DJs use the list for about 60% of the music played while choosing the rest on their own.