California State Route 237
|Defined by Streets and Highways Code § 537|
|Maintained by Caltrans|
|Length:||11.00 mi (17.70 km)|
|West end:||SR 82 in Mountain View|
| SR 85 in Mountain View
US 101 in Sunnyvale
I‑880 in Milpitas
|East end:||I‑680 in Milpitas|
It intersects with Highway 101 at the southern corner of Moffett Field. It also has a major intersection with Interstate 880. Westbound traffic can connect to Highway 85 southbound, but the eastbound traffic connection to 85 northbound is labeled as an exit for U.S. 101.
Half a mile from the highway's western terminus, to the I-880 intersection, Route 237 is constructed to Interstate standards, and is named the Southbay Freeway. It is not part of the Interstate system, however, despite a sign on the ramp to it from Northbound I-680 to the contrary. East of I-880 in Milpitas, it becomes a surface street, Calaveras Boulevard, and the highway designation terminates at the intersection with I-680. West of El Camino Real in Mountain View, it becomes a surface street, Grant Road.
It begins at a junction with El Camino Real (CA-82) in Mountain View as a freeway with two lanes in each direction, although most traffic comes from State Route 85. After an intersection with US Route 101, Mathilda Avenue, and Fair Oaks Avenue, a carpool lane is added for a total of 3 lanes in either direction. It remains like this as it passes the companies where commuters work, to its east end of the freeway at I-880, where most eastbound traffic is directed to northbound 880. The route becomes a street, Calaveras Boulevard, in Milpitas, terminating at I-680. Calaveras Blvd becomes Calaveras Road.
Route 237 is known for the many Silicon Valley companies that line its route.
Before Route 237 was upgraded to freeway status in the mid-1990s, it was a 4-6 lane street, known as Alviso-Milpitas Road or Milpitas-Alviso Road depending on different maps showing the description. Exit signs from U.S. 101 north to Route 237 west currently say "Mountain View-Alviso Road".
The Route 237 corridor has long been sought as a location for a freeway connector between Interstates 680 and 880. Many possible sites have been suggested, from Montague Expressway in North San Jose to Mission Boulevard in Fremont. One map printed before 237's construction to freeway standards between Alviso and 880 showed a new freeway across bay wetlands between Alviso and the Scott Creek Road interchange in South Fremont. Grading and underpasses for a freeway interchange are presently visible along 680 near Scott Creek Road. 
Route 237 is known for a number of companies that define Silicon Valley's technological landscape. Many major software and hardware manufacturers have their headquarters along 237. Some of these manufacturers include Lockheed-Martin, Brocade Communications Systems, Nortel Networks, Cisco Systems, Yahoo!, TiVo, Ariba and NetApp.
Route 237 also passes Moffett Federal Airfield, a large former military air base in the Bay Area.
Highway 237 Bikeway
The Highway 237 Bikeway is a 5-mile (8.0 km) pedestrian and bicycle path that parallels State Route 237. The majority of the path is separated from vehicular traffic, however, two sections comprising a total of 1.5 miles (2.4 km) follow an on-street alignment adjacent the freeway.
This bikeway serves as an important connector in the network of trails in San Jose and Santa Clara County. It intersects with the Guadalupe River Trail, which provides access to Downtown San Jose, as well as the San Tomas Aquino Creek and Coyote Creek trails.
The SR 237 Express Lanes, the 4-mile-long (6.4 km) high-occupancy toll (HOT) lanes along Route 237 in both directions between North First Street in San Jose and I-880 in Milpitas, opened on March 20, 2012. Instead of terminating exactly at the I-880 interchange, the Express Lanes continue along the connector ramp to northbound I-880. Solo drivers are required to pay a toll via a FasTrak transponder. Later on, VTA will add express lanes to SR 85 and US 101.
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 an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see the list of postmile definitions). Segments that remain unconstructed or have been relinquished to local control may be omitted. The entire route is in Santa Clara County.
|Mountain View||R0.00||Grant Road||Continuation beyond SR 82|
|R0.00||1A||SR 82 (El Camino Real) – Mountain View, Los Altos||West end of SR 237|
|West end of freeway|
|R0.38||1A||US 101 north (via SR 85 north) – San Francisco||Eastbound exit and westbound entrance|
|R0.38||1B||SR 85 south to SR 82 south – Los Gatos, Santa Cruz||Westbound exit and eastbound entrance|
|R0.61||1B||Dana Street, Evelyn Avenue, Whisman Road||Signed as exit 1C westbound|
|M1.55||2||Middlefield Road, Maude Avenue|
|Sunnyvale||2.48||3A||US 101 south (Bayshore Freeway) – San Jose||Westbound exit is via exit 3B|
|2.48||3A||US 101 north (Bayshore Freeway) – San Francisco||Eastbound exit is via exit 3B|
|2.99||3B||Mathilda Avenue – Sunnyvale||Former SR 9 south|
|R3.97||4||Fair Oaks Avenue||Eastbound exit and westbound entrance|
|R4.60||5||Lawrence Expressway (CR G2), Caribbean Drive|
|Santa Clara||R5.83||6||Great America Parkway, Lafayette Street|
|San Jose||6.87||7||North First Street|
|9.34||9||I‑880 (Nimitz Freeway) – Oakland, San Jose||Signed as exits 9B (south) and 9C (north)|
|East end of freeway|
|10.00||10||Main Street||Interchange; westbound exit and eastbound entrance; former SR 238|
|11.08||11||I‑680 – Sacramento, San Jose||Interchange; signed as exits 11A (south) and 11B (north); east end of SR 237|
|11.08||Calaveras Boulevard||Continuation beyond I-680|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi
- January 1, 2006 California Log of Bridges on State Highways
- CA Codes (shc:250-257)
- "Highway 237 Bikeway". San Jose Trail Network Website. City of San Jose. Retrieved 2008-03-31.
- "VTA opens Highway 237 express toll lanes". KTVU-TV. 2012-03-20. Retrieved 2012-03-31.
- Staff. "State Truck Route List" (XLS file). California Department of Transportation. Retrieved March 1, 2015.
- California Department of Transportation, Log of Bridges on State Highways, July 2007
- California Department of Transportation, All Traffic Volumes on CSHS, 2005 and 2006
- California Department of Transportation, California Numbered Exit Uniform System, SR-237 Eastbound and SR-237 Westbound, accessed February 2008
- Bay Area FasTrak – includes information on the SR 237 HOT lanes and other toll facilities in the San Francisco Bay Area
- Caltrans: Route 237 highway conditions
- California Highways: SR 237
- Highway 237 / I-880 Interchange Reconstruction Project