California State Route 17

Looking downhill from the Summit Road overpass; brake lights can be seen as cars slow down before the curve known as "Valley Surprise".

SR 17's combination of narrow shoulders, dense traffic, slow trucks, sharp turns, blind curves, wandering fauna such as deer and mountain lions, and sudden changes in traffic speeds have led to a number of collisions and fatalities, leading to the reputation of SR 17 as one of the most dangerous highways in the state. In the winter months, because SR 17 crosses a high precipitation area in the Santa Cruz Mountains, the roadway can become slippery from rain, snow or ice, especially at the summit.

Despite having fewer curves than in Santa Cruz County, certain sections of SR 17 in Santa Clara County are so dangerous that they have been nicknamed. The first long sweeping turn North of Summit Road with its sharp angle, off-camber banking, and steep entering downhill slope is called "Valley Surprise" for the fact that so many strike the median shortly after having entered the Santa Clara Valley. The most infamous is called "Big Moody Curve". This curve is named after Big Moody Creek below, slightly greater than a 180 degree turn, and bracketed by additional 90 degree turns. The inside surfaces of the median barriers in both of these turns are normally chipped up and black with tire rubber.

Efforts to improve safety have included adding electronic speed monitoring signs and warnings lights on curves, removing trees to improve visibility around blind curves, and increased patrol and enforcement of traffic laws. The portion between Los Gatos and Scotts Valley has been designated the Highway 17 Safety Corridor by Caltrans and the California Highway Patrol. In addition, barbed wired fencing and retaining walls were added after the route suffered landslides in the Loma Prieta Earthquake. The route has seen recent repaving work in 2010, 2014, 2019–2020, and 2022-2023.

Gillian Cichowski Memorial Overcrossing Bridge, over SR 17 near Los Gatos at Lexington Reservoir, was named by California Senate Concurrent Resolution 32, Chapt. 70 in 1994. Gillian Cichowski was killed in an accident at this location in 1992. This is one of the few highway constructions in California named for a woman. The overpass was in response to a campaign by friends of Gillian Cichowski to make the intersection (with Bear Creek Road) safer. The overpass was open to northbound traffic July 18, 1996 and opened to southbound traffic August 29, 1996. Margaret Green of Sunnyvale, California died in a similar accident near the same location during overpass construction.

Gillian Cichowski Memorial Overcrossing.

SR 17 in Santa Cruz County is named after California Highway Patrol Lieutenant Michael Walker. Walker was setting flares to direct traffic around an auto accident on New Year's Eve 2005 when he was struck and killed.[8] Partly in response to this accident near the Glenwood Road intersection, Caltrans began work in 2008 to widen the shoulder to eight feet.[9]

The earliest connection between Santa Cruz and San Jose was an old Native American foot trail. The first road that could be navigated by a wagon was a dirt toll road built by Charlie McKiernan,[12] known as "Mountain Charlie" by locals, some time around 1853. Portions of this road still exist as Mountain Charlie Road, to the west of Highway 17 and south of Summit Road. Several other stage lines were built as competitors, such as the San Jose Turnpike (1863), which follows the approximate route of present-day Soquel San Jose Road.[13] After realignment to increase the road width; many sections of the original stage route were cut off. These sections became side streets named with variations containing Old Turnpike. Some of these now dead end streets have retained the look of narrow stage coach roads.

SR 17 was opened in 1940, replacing several other modes of transportation, including the old Glenwood Highway from 1919 (which still exists in Glenwood), and the railroad which went all the way from Santa Cruz to San Francisco and Oakland. The railroad stopped operating in 1940 and the tunnels that it passed through were sealed soon after. Nearly all the tunnel entrances still exist, but are unusable as the tunnels themselves have collapsed. The rise in the use of automobiles made the railroads unprofitable. The city of Glenwood, founded by Charles C. Martin in 1851, gained notoriety for hot springs in the area.[14] The Glenwood Highway, which passed through town, was deserted when the "New 17" was built, and the town became a ghost of its former self.[15] The town's final resident, Mrs. Ed C. Koch, the great-granddaughter of the founder, died in 1992, and Glenwood is a ghost town.

Parts of the original SR 17 lie underwater in Lexington Reservoir. When the reservoir was built, the highway was rerouted to higher ground, and the two towns along its path (Alma and Lexington) were abandoned.[16] When the reservoir levels are extremely low, the old highway pavement is visible as well as some stone and concrete foundations of buildings.

SR 17 first appeared along the east shore of San Francisco Bay in the mid-1930s. The original route between San Jose and Oakland ran along the Old Oakland Road, Main Street (Milpitas) and Warm Springs Boulevard (southern Fremont) proceeding along what is now Fremont Boulevard, which becomes Alvarado Boulevard in Northern Fremont, before entering Union City. From there, the route proceeded along Hesperian Boulevard in Hayward, then into San Leandro via East 14th Street to Davis. It then went west on Davis to Maitland Drive along the southern edge of the Oakland Municipal Airport and across Bay Farm Island to the Bay Farm Island Bridge into Alameda. In Alameda it went via Clay, High, Santa Clara, and Webster to the Posey Tube. SR 17 went through the Posey Tube into Oakland along Harrison Street to 14th, and west on 14th to Broadway where it terminated at a junction with US 40 and SR 24.[17]

Following the completion of the San Francisco-Oakland Bay Bridge in late 1936, SR 17 was re-routed. Instead of turning west at Davis Street in San Leandro, it was continued along East 14th Street into Oakland. At 44th Avenue it turned west, leading to a new diagonal connection to East 12th Street. SR 17 then followed East 12th northward to 14th Avenue, then one block on 14th to East 8th Street, becoming 8th Street into downtown Oakland. It continued west on 8th, picking up a concurrency with Business Route US 50 at Broadway. Both routes continued on 8th to Cypress Street which became an elevated viaduct entering the Bay Bridge Distribution Structure ("The Maze"). SR 17 terminated here at its junction with US 40 (Eastshore Highway) and US 50 (38th Street).[18]

In 1947, work began on a new freeway through Oakland to replace the street routing of SR 17. It was finished in segments, finishing in 1958 with the completion of the double-decked Cypress Structure leading into the MacArthur Maze. The new freeway was called the "Eastshore Freeway", continuous with a planned new freeway north of the Maze to replace the old Eastshore Highway.[19][20] In 1958, the freeway south of the Maze was renamed the "Nimitz Freeway", in honor of WWII Admiral Chester W. Nimitz.[21]

With the completion of the Richmond-San Rafael Bridge in 1956,[22] as well as the first segment of the Eastshore Freeway north of the Maze, SR 17 was extended northward along the new freeway in a concurrency with US 40. SR 17 left the freeway at the Hoffman Blvd. exit (thereafter popularly called the "Hoffman Split") and proceeded along city streets through Richmond to the San Rafael bridge. It went via Hoffman, Cutting, and Standard Avenue up to the bridge. It crossed the bridge into San Rafael, terminating at a junction with US 101.[23][24]

In 1984 the segment of SR 17 from Interstate 280 in San Jose to the Maze (by then known as the "MacArthur Maze") in Oakland was renumbered as I-880, and the portion of SR 17 from the MacArthur Maze to San Rafael was renumbered as part of I-580. SR 17 was thereby reduced to its current length.