Los Angeles

River flowing through southwestern California and the city of Los Angeles, USA; length about 80 km/50 mi. It is formed by several streams in the San Fernando Valley and flows out to San Pedro Bay at Long Beach.

Course The river flows east along the northern side of the Santa Monica Mountains, then turns south into downtown Los Angeles. Its tributaries include the Pacoima River, Tujunga Wash, and the Rio Hondo, which joins it from the east at South Gate.

The Spanish founders of Los Angeles chose a site in 1781 on what they called the Porciúncula River because it did not dry out like other local streams. The river was formerly variable, at times flowing through the ciénagas (marshes) of today's Westside, but has been controlled with dams and channelling.