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How Do You Define the 'Bay Area'?

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An image of the San Francisco Bay Area taken by Samantha Cristoforetti, an Italian crew member aboard the International Space Station.  (Samantha Cristoforetti via Twitter)

It’s the regional name you hear all the time – the San Francisco Bay Area. In more casual conversation, it’s the Bay Area, or the Bay.

But where the boundaries of this region are will vary according to who you ask.

Kristen Goldthorpe and her nephew Chase Osterman have been arguing about this for at least a year. They email each other articles and Osterman sends his aunt memes, like this one.

Goldthorpe is the traditionalist. “The official definition is the nine county definition,” she says.


That’s Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano and Sonoma. Among these nine counties are 101 cities, an estimated 7.756 million people and about 7,000 square miles.

Osterman argues those borders are too broad.

“For me the characteristics are based off geography. If you’re in an area where you can see saltwater – that’s the Bay Area. If you have a bridge, if you get fog from the bay, then that’s the Bay Area,” he says.

So places like Pleasanton? Not in Bay Area by Osterman’s definition. Pleasanton is separated from the water by hills.

Nine counties in the Bay Area
Nine counties in the Bay Area (Bay Area Census)

Part of what makes the Bay Area hard to define is that we have three central cities — Oakland, San Jose and San Francisco.

Yet for some, even those cities are up for debate.

Take for example, my roommate. She doesn’t count San Jose because, so far, it’s not along BART, which is her idea of the Bay Area. Osterman also says San Jose should be considered part of a separate region – Silicon Valley.

While Silicon Valley and the Bay Area are often used interchangeably, data analysts do sometimes group San Francisco and Oakland as a separate metro area from San Jose.

The Origins of ‘The San Francisco Bay Area’

References to the term “The San Francisco Bay Area” first show up on maps in the early 1900s. But the borders weren’t consistent, and some references included Santa Cruz and San Joaquin counties.

“During World War II the region was growing very quickly, and a lot of the industrial development of the region was happening along the Bay shoreline,” says Egon Terplan, the regional planning director at SPUR, a Bay Area civic organization and urban planning policy group. “It was planners during WWII who defined the San Francisco Bay Area as nine counties, and that’s the definition that’s stuck.”

Regional agencies still use the nine county definition. To help you remember each of those nine counties, we asked two local musicians, Alison Faith Levy and Henry Plotnick, to make us a jingle. And oh, is it catchy.

The Nine County Bay Area Jingle!

The Nine County Bay Area Jingle!

But there are other ways to slice and dice where we live.

Expanding the Concept

“There is no kind of perfect definition of what a region is. It really depends what it is we’re trying to define,” Terplan says.

The boundaries might come down to why you’re looking at the Bay Area.

Consider first how the Bay Area is experienced as a commuter.

“As this region has gotten exorbitantly expensive, people continued to move further out both within those nine counties, and then to adjacent counties,” Terplan says.

While these people no longer live in the Bay Area, they still might work, shop, eat and go to church here.

Looking at a map of Bay Area commutes, you’ll see well-worn commute routes extending to Stockton, Modesto, Santa Cruz and even Sacramento. Even if they don’t live within the traditional boundaries, these commuters are part of the Bay Area fabric.

A heat map of commutes in Northern California reveals the urbanized core of the Bay Area, Sacramento and Central Valley cities, as well as the workers who flow into and out of each. Source: Dash Nelson G, Rae A (2016) An Economic Geography of the United States: From Commutes to Megaregions. PLoS ONE 11(11): e0166083. https://doi.org/10.1371/journal.pone.0166083
A heat map of commutes in Northern California. Source: Dash Nelson G, Rae A (2016) An Economic Geography of the United States: From Commutes to Megaregions. PLoS ONE 11(11): e0166083. https://doi.org/10.1371/journal.pone.0166083

Are we more than the nine counties then? Are we 11 counties? Or even more?

Don’t Go Too Far

“We can’t just keep expanding the boundary because at some point you get to the state of California, or you get to the nation, you get to these much larger areas,” Terplan says.

The nine county definition at least puts a limit on it, but if you ask the average person, they have no idea where those county lines are. And honestly, when most people talk about the Bay Area, they’re not talking about economics or county borders, they’re talking about a cultural place.

Defining Us By Our Culture

If we use a cultural lens, how might we define the Bay Area?

Let’s start with food.

You might think California cuisine – the organic, local, farm-to-table goods served at Chez Panisse or The French Laundry. Or you might think of dishes made by the many immigrant groups that have made this place home – lumpia, hand-pulled noodles, injera or tikka masala. Once you start to think about it, there is no one taste of the Bay Area. It’s our diversity that defines us.

Next let’s consider the lens of sports. Do our beloved Golden State Warriors define us? Perhaps wherever you can find Dub Nation, that’s what you can call the Bay? This definition would include places like Fresno, and even pockets of New York City. Fresno is a stretch, though debatable. But New York City? Definitely not the Bay.

Stephen Curry lifts the NBA Championship trophy to Warriors fans lining Lake Merritt. (Adam Grossberg/KQED)

What about music? Growing up, I remember rappers shouting out the Bay Area. I asked rap journalist Eric Arnold where these artists are representing.

“You know Oakland has, I would say, the lion’s share of the talent, but you can find rappers all over the nine counties. There’s been hip-hop that’s come out of San Mateo. There’s been hip-hop that’s come out of Pittsburg,” Arnold says.

Just like it’s hard to identify one Bay Area taste, it’s hard to identify one Bay Area sound, he says. There have been a plethora of styles and eras – too hard to put a boundary around.

Could it be our politics? Bay Area voters do have a reputation, and track record, for being left leaning. Take the 2016 presidential election. The closer you get to the San Francisco Bay, the more “blue” a district gets.

2016 Presidential Election Results
2016 Presidential Election Results ( via LATimes)

“If you look at voting patterns, one of the things that seems pretty strong in the Bay identity is an association with environmental values,” Terplan says. “Every part of the Bay Area has done something to preserve open space at the edges of its community. Santa Clara County has an urban growth boundary, Marin County restricted development on two-thirds of the land, and the East Bay Regional Parks cut across two counties.”

Of course, not everybody is in step with the same politics or environmental values.

What does unite us all? The thing nobody can ignore? How expensive the Bay Area is. Cost of living is a definition that came up over and over again when I asked people how they define the Bay Area.

It’s a pretty grim outlook.

For now, easiest to stick with the nine county definition, but if we’re looking at the Bay Area as a cultural place it’s pretty hard to put a border on that.


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