The call-in talk radio format is one of the key formats of national talk programming. It was first thought to have originated in the early 1970s, when satellite distributed signals made national programs economical and the advent of the 1-800 telephone number allowed for cheaper long distance phone calls. However, this research reveals that the nationwide call-in format originated in 1964 by Herb Jepko, an overnight talk radio host who broadcast his show, Nitecap, from rural Salt Lake City, Utah on one of the country's most powerful clear channel stations, KSL 1160-AM. At the time Nitecap was launched, most radio executives were skeptical that national call-in talk radio could be successful. Yet, Jepko demonstrated that millions of people, awake in the late and early morning hours, were interested in listening to radio programming as well as interacting with the host and other listeners. This research examines Jepko's innovation of national call-in talk radio and the factors that contributed to his success. He altered the traditional talk radio paradigm and changed the way industry leaders viewed both the overnight time slot and national call-in talk shows. His work set the foundation for the format and paved the way for its use today.