What was the first hour-long Western on American TV?

The first hour-long Western on American TV was "Cheyenne". It was a Western TV series that provided a 108 black-and-white episodes, shown on the ABC Network from 1955 to 1962. "Cheyenne" was also the first hour-long dramatic series of any kind, with continuing characters, to last more than one season.

The show was the first TV series to be made by a major Hollywood film studio that was not connected with an established big screen film entity. The series became the first of a long chain of Warner Bros. original series produced by William T. Orr.

"Cheyenne" starred Clint Walker as Cheyenne Bodie. He was a physically large cowboy with a gentle spirit in search of frontier justice. He wanders the American West in the days after the American Civil War. The first episode, "Mountain Fortress", is about robbers pretending to be Good Samaritans. The episode reveals that Bodie's parents were killed when he was a young boy. He was taken by Cheyenne braves when he was 10 years old. The Native American tribe, a powerful, resourceful tribe of the Great Plains, who fiercely resisted any encroachment of their land, raised him. He left the tribe by choice when he was 18 years old. In the series, Bodie maintains a positive and understanding attitude toward the Native Americans, despite their role in the death of his parents.