A uniform numbering system has been adopted to uniquely identify county routes across the state of California. Within this system, each route designation has a letter and number combination. The first digit is a letter, and the second and third digits are numbers. The lower letters are generally to the north of the state, and the higher numbers are generally located in the southern part of the state. The lowest route is Lassen County Route A-1, and the highest route is Imperial County Route S-80.
County Route Group S -- along with Groups N, P, and R -- are in the Southern California group of counties: Imperial, Inyo, Los Angeles, Mono, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura. The letters O and Q are omitted, and county routes in Group P have not been assigned.
San Diego County Route S-12 - Palomar Airport Road/Encinitas Road/Twin Oaks Valley Road/Deer Springs Road
San Diego County Route S-13 - Vista Way/Mission Road/Historic U.S. 395
San Diego County Route S-14 - Mission Road/Santa Fe Avenue
San Diego County Route S-15 - Fallbrook Street/Reche Road
San Diego and Riverside County Route S-16 - Pala Temecula Road/Pala Road
San Diego County Route S-17 - Bonita Road/Jamacha Road/Sweetwater Road/Jamacha Boulevard
San Diego County Route S-17 begins at the E Street interchange with Interstate 5 in Chula Vista. This overhead sign for Interstate 5 is posted on eastbound on the freeway overpass. As typical, County Route S-17 is not signed on the overhead guide sign. Photo taken 01/18/09.
Eastbound San Diego County Route S-17 approaching Sweetwater Road after the bridge over the Sweetwater River in unincorporated Bonita. Photo taken 12/19/02.
Eastbound San Diego County Route S-17 at Sweetwater Road. The route is well-signed through Bonita. Photo taken 12/19/02.
Eastbound San Diego County Route S-17 passes near Bonita Golf Course. The county road was impacted during construction of the California 125 freeway extension; note the California 125 construction sign. The toll road was completed and opened to traffic in late 2007. Photo taken 12/19/02.
Eastbound San Diego County Route S-17/Sweetwater Road approaching junction California 54 near Spring Valley. Although County Route S-17 merges onto California 54 to reach Jamacha Road, it is not well-signed, especially given the construction of the new California 54-125 freeway interchange. Photo taken 12/19/02.
Eastbound San Diego County Route S-17 at Junction California 54/South Bay Freeway. This signal will be replaced with an interchange once the conversion of California 54 to a freeway between Interstate 805 and California 125 is complete. Photo taken 12/19/02.
Northbound San Diego County Route S-17 at Junction California 94. Although this shield assembly implies that County Route S-17 merges with California 94, this is the last shield along eastbound (northbound). The remainder of the original County Route S-17 is signed as California 54 or Business Route 54 through unincorporated Rancho San Diego and the city of El Cajon. Photo taken 12/19/02.
Orange County Route S-18 - El Toro Road/Santiago Canyon Road north
Northbound Orange County Route S-18 approaches its junction with California 73/San Joaquin Transportation Corridor Toll Road south to San Clemente. Photo taken 03/30/03.
Orange County Route S-18 meets the California 73 Toll Road at this intersection. Photo taken 03/30/03.
An Orange County Route S-18 reassurance shield is posted along northbound El Toro Road after the Interstate 5 interchange. Photo taken 07/13/09.
Orange County Route S-18 - El Toro Road/Santiago Canyon Road south
In Lake Forest, southbound Orange County Route S-18/El Toro Road approaches its junction with Interstate 5. The first ramp connects to Interstate 5 north to Santa Ana and Los Angeles. Photo taken 07/13/09.
Southbound Orange County Route S-18 approaching Junction Northbound California 73/Toll Road. Photo taken 03/30/03.
San Diego County Route S-21/Old U.S. Highway 101, known as Genesee Avenue, North Torrey Pines Road, Camino del Mar, Coast Highway 101, Carlsbad Boulevard, Coast Highway (For history, guide, and information, see Historic U.S. 101)
San Diego and Imperial County Route S-22/Montezuma Valley Road, Palm Canyon Drive, Peg Leg Road, and Borrego-Salton Seaway
View of eastbound San Diego County Route S-22 at Milepost 4. Photo taken 05/29/02.
Eastbound San Diego County Route S-22 at Milepost 12.4 near the Borrego Springs overlook. Photo taken 05/29/02.
Signage at the overlook that looks over Borrego Springs in Anza Borrego State Park. We spotted a peninsular big horn sheep at this overlook on the day this photo was taken. Photo taken 05/29/02.
View of Borrego Springs and the Anza Borrego State Park as seen from the overlook adjacent to San Diego County Route S-22. Photo taken 05/29/02.
Westbound San Diego County Route S-22 at the overlook above Borrego Springs. Photo taken 05/29/02.
Eastbound San Diego County Route S-22 at Junction San Diego County Route S-3 at the Christmas Circle in Borrego Springs. Photo taken 05/29/02.
Close-up of the San Diego County Route S-22 shield at its junction with San Diego County Route S-3 at the Christmas Circle in Borrego Springs. Photo taken 05/29/02.
