SR 371 was part of SR 71 until 1973, when SR 79 and SR 71 were co-signed from Temecula to Aguanga to Temecula. In 1974, the portion of SR 71 from Temecula to Corona along I-15's current alignment was deleted, and the orphaned route from Aguanga to Anza was re-signed as SR 371.
SR 371 begins as Cahuilla Road at an intersection with SR 79. It travels northeast away from the community of Aguanga, loosely paralleling Tule Creek for the first few miles. SR 371 continues through the Lake Riverside community, crossing over the outflow of the lake. The highway enters the Cahuilla Indian Reservation and passes by the Cahuilla Creek Casino in Cahuilla before passing through the community of Anza. SR 371 briefly becomes Kenworthy Bautista Road and parallels Hamilton Creek as it enters the San Bernardino National Forest before terminating at SR 74.[1]
Route 277 from Temecula to Anza was added to the state highway system in 1959.[4] In the 1964 state highway renumbering, the part from US 395 to SR 74 was included as part of SR 71.[5] In 1974, the part from near Aguanga to SR 74 became SR 371.[6]
Before 2003, the intersection with SR 79 was very dangerous, as northbound SR 79 traffic had to stop at a stop sign and there was no such sign for southbound SR 79 traffic or for SR 371 traffic headed towards its western terminus. Now, there are stop signs in every direction at that intersection.
