Lowry Mays, a businessman who inadvertently acquired a local radio station in the early 1970s, then built it into a media empire called Clear Channel that revolutionized the entire industry, died in San Antonio.

Mr. Mays was a petroleum engineer turned investment banker when he agreed in 1972 to co-sign a loan to purchase KEEZ, an FM station struggling to survive at a time when most people still listened to AM. When the original buyers backed out, Mr. Mays and his business partner, Billy Joe McCombs, were left owning a property they had no interest, let alone experience, in operating.