Discover The Longest Bridge In California — A 7-Mile Behemoth!

Written by Crystal
Updated: May 31, 2023
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What’s the longest bridge in California?

If you guessed the Golden Gate Bridge, think again. Spanning 7 miles, the San Mateo-Hayward bridge is the longest in California. The story behind this crossing dates back to the early 1920s and has a lot of twists and turns! What do you need to know about this incredibly long bridge? Read on to find out.

History Of The San Mateo–Hayward Bridge

The San Mateo–Hayward Bridge was first proposed in 1922 by the Oakland Chamber of Commerce. The goal was to encourage commerce between the Peninsula and East Bay.

The original bridge plans didn’t mention Hayward. However, this initial proposal was enough to get the ball rolling in the transportation department. State leaders began to see the need for an automated crossing for the middle section of San Francisco Bay.

San Mateo Hayward Bridge
The longest bridge in California is the San Mateo-Hayward Bridge, which stretches seven miles and has a total of six lanes.


Dumbarton Bridge 1927

Before constructing the San Mateo–Hayward Bridge, California constructed the Dumbarton Bridge in 1927. By the late 1920s, the San Francisco toll bridge company was also raising money for the section covering Hayward to San Mateo.

San Francisco Bay Toll Bridge 1927

Construction for the long toll bridge began in December 1927. By March, they were already harvesting oysters for the cement mixture.

Why oysters? Oyster shells contain calcium carbonate, a common substance found in rocks. For instance, limestone, chalk, and marble all contain calcium carbonate. This chemical compound also occurs in organic materials like eggshells and oyster shells.

Calcium carbonate helps improve the strength of the bridge in a few ways. It makes the bridge more durable and improves freeze-thaw resistance. Oyster shells also have better water permeability than standard concrete.

Finally, $7.5 million later, the San Francisco Bay toll bridge was ready to open in March 1929. The bridge was 7 miles long, but it was less extravagant than the bridge that stands today.

The original bridge was only 35 feet above the water and was narrow. With a clearance that was 30 feet wide, the toll bridge had just enough room to fit in two lanes. There weren’t even any shoulder areas for disabled vehicles to stop on. Drivers had to hope for the best, which didn’t always work out. Soon, traffic congestion was a significant issue.

Traffic Congestion Becomes A Major Problem

As the longest bridge in California, the San Mateo–Hayward Bridge, grew in popularity, and so did the traffic congestion. Things got so bad that during the 1950s, bridge traffic was a hot topic among politicians. This put pressure on the state leaders to find a solution.

In 1951, the state of California purchased the Hayward San Mateo Bridge and Dumbarton Bridge for $8.35 million. They lowered tolls to 35 cents to celebrate the purchase but still needed a way to improve traffic flow.

Aerail view of the San Mateo-Hayward Bridge
The longest bridge in California offers a section for ships to cross underneath.


A Solution Arises

By 1957, traffic problems were at an all-time high. Driver’s trying to cross the bridge would wind up at a standstill as many as six times a day. State leaders understood that the area had outgrown the original bridge, and it was time to lay the groundwork for new construction. Construction for a new, wider bridge began in 1961.

Hayward San Mateo Bridge Reopens

In October of 1967, the Hayward San Mateo Bridge reopened. After 6 years and $70 million, the new bridge included two lanes in each direction. It also featured a high-rise section 135 feet above a dredged channel. Now ships could easily pass underneath the bridge without interrupting traffic.

Excited by the success, Bay Area voters approved raising tolls to help fund more bridge improvements. This was in 1988, and tolls were raised on the Bay area’s seven state-owned toll bridges.

San Mateo-Hayward Bridge Today

Since 1967, the bridge has had multiple extensions to prevent traffic jams. One of the widening parts of the bridge was in January 2003 and had a tremendous impact on traffic flow. Another one of the bridge’s improvements was completed in October 2011. The original structure only cost $7.5 million, but the expansive infrastructure has cost the state around $200 million.

Six Lane Success

Now, the San Mateo–Hayward Bridge has six lanes. The widened bridge has made evening commutes on State Route 92 much more enjoyable. And the new bridge is also a lot safer. Now there are full shoulders along both low-rise trestles. If a car breaks down, they have a safe place to wait for roadside assistance.

Millions in Tolls Are Collected Each Year

Over 13 million toll-paid vehicles cross the bridge annually. This earns over $100 million for the state of California. There are multiple ways for drivers to pay these tolls. A few options include license plate accounts, one-time payments, invoices, and FasTrak.

Nightly view of the San-Mateo Hayward Bridge with electricity towers in view
The longest bridge in California has a curve in the structure, which is thanks to the girder design of the bridge.


New Better Looking Design

The San Mateo–Hayward Bridge isn’t just wider; it’s also prettier. The institute of steel construction awarded the bridge the title of the most beautiful bridge long span, thanks to the soft curves.

The engineering on this bridge is remarkable too. Closely resembling an ancient beam bridge, the San Mateo–Hayward Bridge is a girder bridge.

Girder bridges are one of the simplest and sturdiest bridge structures. The girder bridge design is the reason why the San Mateo-Hayward bridge can have horizontal curves without compromising the crossing’s structural integrity.

Bridge Length

The total length of the San Mateo–Hayward Bridge is 7 miles. This includes 1.9 mi on the western side high-rise section. There are also 5.1 miles for the trestle section on the eastern side. The vertical clearance is 135 feet, and the channel span is 750 feet.

Exactly Where Is The Bridge Located?

The San Mateo–Hayward Bridge is located on State Route 92 between San Mateo and Alameda counties. The bridge stretches 7 miles from Foster City to Hayward across the San Francisco Bay.

The city of Hayward is in Alameda County; it’s a suburb of San Mateo. In contrast, Foster City sits at the bridge’s western end, between San Francisco Bay and the Bayshore Freeway US 101. It’s a group of islands with an extensive network of lagoons winding through the city.

What Wildlife Lives Underneath The Bridge?

There are over 500 fish species that live beneath the San Mateo–Hayward Bridge. There are also sharks, shrimp, oysters, and more there. Sharks living in these waters include the pacific angel, leopard, brown smoothhound, and others.

Marine Mammals

Marine mammals also live under the bridge, like bottlenose dolphins and a variety of seals. Sea lions are always hanging out around San Francisco bay. While the California sea lions are only seasonal, the pacific harbor seals stay year-round. Close to 46,000 harbor seals live along the coast of California.

Bird Species

All sorts of raptors patrol the shoreline. As you cross the longest bridge in California, keep your eyes open for osprey, cooper’s hawk, red-tailed hawk, prairie falcons, and merlins. You might even be lucky enough to spot a migrating bald eagle.

Other birds that frequent the area include cattle egrets, snow geese, Virginia’s warbler, and Harley Quinn ducks. The best birding opportunities are October through March since the water birds winter by the thousands.

Aerial view of the San Mateo-Hayward Bridge
The San Mateo-Hayward Bridge was built to cross San Francisco Bay and provide a convenient commute.


Final Thoughts On The San Mateo–Hayward Bridge

Now you know the story behind the longest bridge in California, the San Mateo–Hayward Bridge. What began as a narrow two-lane span has grown into a convenient six-lane highway, with three lanes in each direction. There are also shoulders on the bridge for disabled vehicles.

Overall, this bridge has been a major success for the state. Now there’s a way for drivers to pass the middle section of San Francisco Bay easily, and the toll money collected is substantial. Around 81,000 vehicles pass the bridge daily, providing California with millions in tolls each year.

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The Featured Image

Aerial view of the San Mateo-Hayward Bridge
Aerial view of San Mateo Bridge crossing the San Francisco Bay

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About the Author

Crystal is always looking to learn more, and share her finds with you along the way. It's amazing how you can spend your entire life living with plants and animals, but still know so little about them! Let's explore our world together as Crystal covers topics about creatures, places, and experiences.

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