Rochester, MN (KROC-AM News)- On September 30, 1935 KROC-AM became the first radio station to hit the airwaves in Rochester. He came for his son, who was getting care at Mayo Clinic. Lou GehrigA stay at Mayo Clinic also led to an interview for one of baseball's all-time greats. The two main employers responsible are Mayo Clinic and IBM. The Mayo Clinic in Rocheste r, Minnesota has seen quite a few throughout its history.