he fourth season of One Tree Hill began airing on September 27, 2006. The season concluded June 13, 2007, after 21 episodes. This is the first season to air on the newly formed The CW television network.
Season four regular cast members include Chad Michael Murray, James Lafferty, Hilarie Burton, Bethany Joy Galeotti, Paul Johansson, Sophia Bush, Barbara Alyn Woods, Lee Norris, Antwon Tanner, Danneel Harris, Barry Corbin, and Moira Kelly.
The season picks up directly after the events of the season three finale car accident. It focuses on the remainder of senior year at Tree Hill High and ends with the graduation of the teenage characters. In this season, most episodes were named after rock albums rather than after songs. Season four rose in ratings, averaging 2.9 million viewers weekly, becoming #136 in the Nielsen ratings system.Overview from themoviedb.org