Which American TV show was the first to have reruns (rebroadcasts)?

A "rerun" is a rebroadcast of an episode of a radio or television program. There are two types of reruns – those that occur during a hiatus, and those that occur when a program is syndicated.

Lucille Ball (August 6, 1911 – April 26, 1989) and Desi Arnaz (March 2, 1917 – December 2, 1986) are generally credited as the inventors of the rerun; it was first utilized for the American television series "I Love Lucy" (1951–57) during Ball's pregnancy.

Prior to "I Love Lucy" rerunning its episodes during the summer, shows typically went on a summer hiatus and were replaced with summer replacement programming. These shows were generally lower-priority programs. This strategy has seen increased use in the 21st century as fewer episodes of modern day shows have been produced each season and in-season reruns have increased.

In the United States, most television shows from the late 1940s and early 1950s were performed live, and in many cases they were never recorded. However, television networks in the United States began making kinescope recordings of shows broadcast live from the East Coast. This allowed the show to be broadcast later for the West Coast. These kinescopes, along with pre-filmed shows, and later, videotape, paved the way for extensive reruns of syndicated television series.