California State Route 108

State Route 108 begins in downtown Modesto at the junction of SR 99 and SR 132, overlapping SR 132 for several blocks northeast on L Street to 9th Street. There it splits into a short one-way pair, with eastbound SR 108 turning southeast with SR 132 on 9th Street to K Street and then northeast to Needham Street; the westbound direction remains on L Street to Needham Street. After several blocks eastward on Needham Street, SR 108 reaches McHenry Avenue, which it follows north out of the city. There is no route marker eastbound indicating where the route turns left from 9th Street to K Street, nor is there a route marker indicating where the westbound traffic turns left from Needham Street to L Street.

From Modesto, SR 108 runs north along McHenry Avenue for about 7 miles (11 km) before turning eastward on Patterson Road to follow the Stanislaus River east-northeast. In Riverbank, County Route J7 comes from the north and departs to the south after about a one-mile (1.6 km) co-routing. After following the river about 10 miles (16 km), SR 108 passes straight through the heart of downtown Oakdale.

At the main intersection in Oakdale, SR 120 joins SR 108 from the north and they are co-signed as they continue northeast, climbing into the foothills and passing just south of Knights Ferry. SR 120 brings with it the title Northern Yosemite Highway for this segment; with State Route 140 being the middle route from the west and State Route 41 being the southern route to Yosemite. Just past Knights Ferry, SR 108 crosses from Stanislaus County into Tuolumne County, and the road changes from two lanes to four-lane separated highway for about 6 miles (9.7 km). This is advantageous as steep grade is located along this stretch of the road and the extra lanes are useful as passing lanes both ascending and descending the mountain range. About a mile after the end of the separated pavement, La Grange Road (County road J59) heads south, passing just west of Lake Don Pedro and meeting SR 132 near the town of La Grange. Another 3 miles (4.8 km) eastward, at Yosemite Junction, SR 120 finally separates from SR 108 and heads southward toward to a co-routing with State Route 49 through Chinese Camp and across the upper end of Lake Don Pedro.

California 108 near Sonora Pass

Another 3 miles (4.8 km) eastward, SR 49 joins from the south and is co-routed with SR 108 through Jamestown and into Sonora, where SR 49 departs to the north. SR 108 continues eastward and gains elevation as it passes through Twain Harte, Mi-Wuk Village, Long Barn, Cold Springs, Strawberry-Pinecrest Lake and Dodge Ridge Ski Area, then on to Dardanelle and Kennedy Meadow. SR 108 passes through Alpine County for approximately 0.8 miles immediately west of the Sonora Pass. At the pass, the highway crosses the summit of the Sierra Nevada and enters Mono County, then descends past the Mountain Warfare Training Center at Pickel Meadows, finally reaching the eastern terminus at Sonora Junction where it meets U.S. Route 395. Sonora Pass usually closes during the winter months, often from November through as late as May.[2]

SR 108 is part of the California Freeway and Expressway System,[3] and west of the eastern junction with SR 49 is part of the National Highway System,[4] a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration.[5] SR 108 is eligible to be included in the State Scenic Highway System,[6] but it is not officially designated as a scenic highway by the California Department of Transportation.[7]

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers to an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see California postmile § Official postmile definitions).[8] Segments that remain unconstructed or have been relinquished to local control may be omitted. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.

County	Location	Postmile [8][1][9]	Destinations	Notes
Stanislaus STA 14.73[N 1]-T18.17[N 2]	Modesto	14.73[N 1]	Maze Boulevard	Continuation beyond SR 99; former SR 132 west
		14.73[N 1]	SR 99 / SR 132 west – Stockton, Merced, Vernalis	Interchange; west end of SR 132 overlap; west end of SR 108; SR 99 north exit 226, south exit 226B
		15.06[N 1] R22.44	SR 132 east (9th Street) – Coulterville	East end of SR 132 overlap; serves Modesto City-County Airport
		24.81	Briggsmore Avenue
		26.06	Standiford Avenue, Sylvan Avenue
	​	27.62	SR 219 west (Kiernan Avenue) to SR 99 / Claribel Road – Salida
	​	29.15	CR J6 (McHenry Avenue) – Escalon
	Riverbank	31.05	Oakdale Road
		32.44	CR J7 north (1st Street)	West end of CR J7 overlap
	​	33.38	CR J7 south (Claus Road)	East end of CR J7 overlap
	Oakdale	38.24 5.12[N 2]	SR 120 west / CR J9 / CR J14 (Yosemite Avenue) – Escalon, Manteca	West end of SR 120 overlap
Tuolumne TUO R0.00[N 2]-66.97	​	8.19[N 2]	CR J59 (La Grange Road) – La Grange, Merced
	​	​	CR E15 (O'Byrnes Ferry Road) – Copperopolis
	​	12.08[N 2] L0.00	SR 120 east – Chinese Camp, Groveland, Yosemite	East end of SR 120 overlap
	​	L2.81 R11.59[N 3]	SR 49 south – Chinese Camp, Yosemite	West end of SR 49 overlap
	Jamestown	14.74[N 3]	CR E5 (Rawhide Road) / Humbug Street
	Sonora	16.48[N 3] R0.00	SR 49 north (Stockton Street, SR 108 Bus. east) – Downtown Sonora, Angels Camp	Interchange; east end of SR 49 overlap; former SR 108 east; west end of Sonora bypass
	​	R2.20	SR 108 Bus. (Mono Way)	Interchange; former SR 108
	​	R3.42	Hess Avenue, Phoenix Lake Road	Interchange
	​	R4.50	Peaceful Oak Road, Standard Road	Interchange
	​	R5.50	SR 108 Bus. west (Mono Way)	Former SR 108 west; east end of Sonora bypass
	​	7.51	Soulsbyville Road – Mono Vista, Soulsbyville, Willow Springs, Tuolumne City
	​	R9.58	Twain Harte Drive (SR 108 Bus. east), Plainview Road – Twain Harte
	Twain Harte	R11.75	CR E17 (Tuolumne Road) / Twain Harte Drive (SR 108 Bus. west) – Twain Harte
	​	38.78	Eastbound winter closure gate
Tuolumne–Mono county line	​	66.97 0.00	Sonora Pass (closed in winters), elevation 9,624 feet (2,933 m)[10]
Mono MNO 0.00-15.15	Pickel Meadows	9.82	Westbound winter closure gate
	​	15.15	US 395 – Walker, Carson City, Bridgeport, Bishop	East end of SR 108
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access

•  California Roads portal

• Caltrans: State Route 108 highway conditions
• Caltrans Traffic Conditions Map
• California Highway Patrol Traffic Incidents
• California Highways: Route 108
• AARoads: State Route 108