California State Route 37

A view of the Mare Island bridge from SR 37

SR 37 outside of Mare Island

As late as 1926, Golden Gate Ferries, owners of the Sears Point Toll Road Co., began plans to build the Sears Point Toll Road,[17] with a contract awarded to Oakland-based Hutchinson Company in October 1927.[20] The paved toll road was to be built on top of an ancient Native American trail[3] along the San Pablo Bay shore between the Sacramento Highway and the Black Point cut-off (LRN 8) near Sears Point. It was expected to cost $775,000USD, with a toll not exceeding $0.35. Toll road officials explained the purpose of the road; to stimulate motor vehicle usage by reducing the commute times and expenses of motorists traveling from the East Bay and Sacramento areas by offering a more direct route toward Marin, Sonoma and the Redwood Highway.[20] The road opened for traffic in 1928.[3]

On November 29, 1932, the California State Highway Commission received a recommendation to purchase the road[21] and was able to invest $418,000USD by 1936. However, the U.S. Navy owned rights to the right-of-way of part of the route, and opposed the purchase. This resulted in congressional actions to establish a clear title deed for the route.[22][23] House Representative Richard J. Welch was one of the earliest government officials to pressure the State of California to acquire the toll road in order to convert it into a toll-free highway. He argued that having only one toll road to travel in order to reach the Golden Gate Bridge would benefit commuters; he also cited the ten and seventh-tenths-mile difference in distance between the toll road and a route through Napa.[24] A Navy Department deed permitting the State to purchase the road was granted by the Attorney General on October 26, 1938.[25] The highway then became signed as State Route 48 until the 1964 renumbering.[16]

The Lone Toilet on Highway 37 near Sears Point Rd 01

By 1955, talks began about upgrading the highway.[3] After a proposition to turn much of the route into a toll road failed, it was decided a four-lane freeway would be the best decision. However, opposition from residents in surrounding neighborhoods as well as a federal oil embargo only allowed widening of the approach between Fairgrounds Drive and I-80. In 1977, a levee broke and flooded a portion of the developed land, turning it into protected wetlands that is home to endangered species. Because of its new status, environmental studies were needed in order to continue the project.[7]

Soon after, the project was split into different phases[5] to handle problems with particular areas. It was first divided between the newly created marshlands and the section between Sonoma Blvd. (SR 29) and I-80. With Marine World being relocated, the city was able to the widen the latter section and build an overpass across Fairgrounds Drive in 1992.[7]

This section of SR 37 was once known as "Blood Alley" for its rate of fatal accidents

While the Vallejo section of SR 37 was being updated, another problem with the route would hinder its progress. The section between Sears Point and Mare Island was plagued with fatal accidents, earning its nickname of "Blood Alley". Between 1966 and 1970, 27 people lost their lives on it. In a preliminary effort to reduce the fatalities, officials established both a daylight test section, requiring all cars to keep their headlights on during the day, and passing lanes. However, these efforts were ineffective.[26]

In 1993, local resident Jim Poulos campaigned to have a barrier erected after the death of his 18-year-old son, Frankie, on "Blood Alley". At this time, the situation with this stretch only worsened as the death toll between 1990 and 1996 rose to thirty-one. At first, Caltrans thought the barrier would make matters worse since it would be difficult for emergency vehicles to attend to accidents; environmental issues were also cited. Caltrans was waiting for the ability to create a causeway to span the area instead. Poulos continued his campaign despite opposition, and was granted the barrier in 1995. The barrier was not built without controversy, as it also eliminated the passing lanes. However, since the barriers were built, there were no longer any crossover accidents as of 2005.[3]

While the median was built, a few problems needed to be resolved in order for the road to work both safely and in an environmentally friendly way. Emergency personnel needed to quickly access accidents and provide them easy transport to nearby hospitals. To alleviate this problem, Caltrans implemented electric gate technology, which would allow emergency vehicles to cut through certain parts of the median. The other problem was to both protect the plant life and the salt marsh harvest mice residing around the highway. As a result, crews placed timbers and sheeting to protect foliage, and added holes into the median barrier to allow the mice to cross the highway.[27]

Display of the various components of the project including the SR 37/SR 29 interchange.

To protect White Slough while still allowing the widening of SR 37, the White Slough Protection and Development Act was passed in 1990.[28] It allowed up to 13 acres of wetlands to be filled but required at least four times as much wetland restoration elsewhere in the Bay Area.[28]

After environmental studies on the White Slough, Caltrans widened and elevated that section of the road and converted it to a freeway. To accommodate bicycles and pedestrians, a cycleway was built along the eastbound side of the freeway. Finally, Caltrans completed the overpass which crossed SR 29, Broadway, and Mini Drive (bypassing Marine World Parkway, three traffic signaled intersections, and a railroad grade crossing). The project was completed in the summer of 2005,[7] and fully open to traffic on August 20.[29]

Looking at San Pablo Bay National Wildlife Refuge from SR 37

The highway is increasingly subject to flooding as the 21-mile (34 km) route is near sea level.[30][31] The road was closed for a total of 28 days during the winter of 2016-17.[31]

On the morning of Friday February 15, 2019, the westernmost portion of the westbound highway (between Atherton Ave. and U.S. Route 101) was closed due to flooding caused by a levee break.[32] Marin County declared a state of emergency, and public works crews worked 24 hours a day pumping water and repairing the levee.[33] It was expected to be closed for at least a week,[34] however the highway fully reopened on the morning of Wednesday, February 20, 2019.[35]

In 2017, it was estimated that it would cost $4 billion to fix all the flooding, traffic, and other issues along the corridor, and based on transportation funding levels it would take until 2088 to come up with that amount of money.[36][31]

In 2022, California State Senator Bill Dodd introduced new legislation that would make the route a toll road again between Sears Point and at least Mare Island. The proposed law would use the toll revenues to help pay for the flooding and traffic improvements.[37] It has been opposed by a number of commuters, particular Solano county residents who commute west to jobs in Sonoma or Marin counties.[38] In May 2023, the California Transportation Commission unanimously approved a plan to toll both directions, as well as widen the highway from a two-lane road to one with carpool lanes by converting the existing shoulders.[39]