Two of the largest public radio networks, Minnesota Public Radio (MPR) and Public Radio International (PRI), are based in the state. MPR has the largest audience of any regional public radio network in the nation, broadcasting on 46 radio stations as of 2019. PRI weekly provides more than 400 hours of programming to almost 800 affiliates. The state's oldest radio station, KUOM-AM, was launched in 1922 and is among the 10-oldest radio stations in the United States. The University of Minnesota-owned station is still on the air, and since 1993 broadcasts a college rock format.