Democrats now control all House seats along the Pacific Ocean for first time in memory

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The West Coast has long been dominated by Democratic politicians — it’s referred to the Left Coast for a reason.

But for the first time in modern memory, Democrats are set to control every congressional district along the Pacific Coast.

It’s a feat Democrats “haven’t accomplished since before Washington became a state in 1889,” according to the left-leaning publication Daily Kos.

Dave Wasserman, a congressional race analyst with the nonpartisan Cook Political Report, also spotted the trend, forecasting on Twitter before all races were called that 2023 would “be the first time Republicans are shut out of every district touching the Pacific Ocean.”

The blue wave along the Pacific Coast was made possible by an upset in southern Washington, a recently flipped seat in Alaska and two key Southern California victories — even as Democrats lost control of the House of Representatives to a narrow Republican majority.

The trend reflects “the increased polarization in American politics,” said Eric Schickler, a professor of political scientist at the University of California, Berkeley.

“While some of these districts may well be won by Republicans in future elections, it does symbolize the broader division between coastal America — both on the east and west coasts — and inland areas,” Schickler said.

The key was the surprise Democratic victory in Washington’s 3rd Congressional District, where Marie Gluesenkamp Perez defeated Donald Trump-endorsed Republican Joe Kent. An auto shop owner who was largely unknown before announcing her campaign, Gluesenkamp Perez “pulled off perhaps the most stunning political upset in the country this year,” the Seattle Times reported.

In Alaska, Democrat Mary Peltola held onto the state’s sole congressional district, a seat she flipped in a September special election. Peltola, who is the first Alaska Native member of Congress, defeated Sarah Palin to replace Republican Don Young, who held the seat for 49 years until his death earlier this year.

Other key wins that handed the West Coast to the Democrats came in the Los Angeles area, where redistricting reshuffled the historically Republican-leaning Orange County coastline.

Despite being drawn into a different district, Orange County Rep. Katie Porter, a well-financed rising star in the Democratic Party, defeatedScott Baugh, who once served as the top Republican in the Assembly. Cook Political Report had rated the race for California’s 47th Congressional District as a “toss-up” a week before Election Day. The Associated Press called the race for Porter last week.

To the south, in California’s 49th Congressional District spanning parts of Orange and San Diego counties, incumbent Democrat Rep. Mike Levin defeated Republican challenger Brian Maryott with 53% of the vote at latest count.

The pattern in Pacific states of coastal areas being predominantly Democrat and the interior areas leaning Republican has been a reality for decades, said Bruce Cain, a Stanford political scientist — and it is unlikely to change, he said, as people increasingly live “near others that share similar social, economic and political orientations.”

Nora Mishanec is a San Francisco Chronicle staff writer. Email: [email protected]