WMPX is simulcast with WMRX-FM 97.7 24/7 except for some local sports play-by-play. Although there are other radio stations licensed to Midland, WMPX is today the only commercial radio station that primarily serves the Midland area (WUGN-FM is a non-commercial religious station and WKQZ-FM is licensed to Midland but has studios in Saginaw).
WMPX began broadcasting in 1948 as WMDN. WMDN was Midland's first radio station, owned by the city's newspaper, the Midland Daily News. That station continued to use that callsign until July 1971. (The WMDN calls are now used for a television station in Meridian, Mississippi.)