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Even that earlier example was something of a fluke. Democrats won all six of California’s House seats in 1882, when Republicans nationwide lost almost three dozen seats in the first midterm after Vice President Chester A. Arthur replaced Republican President James Garfield, who had been assassinated in the summer of 1881.

But by 1884, when the state backed GOP nominee James Blaine in the presidential race, Republicans had rebounded to win five of California’s six seats.

Apart from that one slip in the early 1880s, Republicans since the Civil War have never fallen as far in the state’s congressional delegation as they have now. Even during the depths of the Depression, Republicans never fell below one-fifth of the state’s House seats, according to the Target Book data.

During the Watergate-backlash election of 1974, Republicans retreated to just over one-third of the state’s delegation, still more than double its share now. Before this month’s results, California Republicans had not held less than just over one-quarter of the state’s congressional seats at any point since 1938.

The GOP’s retreat in California long predated Trump, but there’s no question he has intensified and accelerated it. In the past two years, California House Republicans, under pressure from then–Majority Leader Kevin McCarthy of Bakersfield, compounded their risk by voting with Trump more reliably than their Republican counterparts in other blue-leaning coastal states such as New York, New Jersey, and Pennsylvania.

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“They bet on Trump and they bet wrong,” says John J. Pitney, a Claremont McKenna University political scientist and former aide at the Republican National Committee.

It’s difficult to imagine now, but for most of its early history, California leaned Republican. Other than Franklin D. Roosevelt and Harry Truman, Democratic presidential candidates carried the state only three times from 1860 through 1960.

After Lyndon Johnson’s landslide win in 1964, Republicans again won California six straight times from 1968 through 1988, with native sons Richard Nixon and Ronald Reagan as the presidential nominee in four of those races.

In the late 19th century, California largely alternated between Republican and Democratic governors, but the GOP seized the advantage during the Progressive Era (through figures such as Hiram Johnson) and maintained it though the heart of the 20th century: Democrats controlled the governorship for only three terms from 1899 through 1974. And after the iconoclastic Democrat Jerry Brown won two terms as governor from 1974 through 1982, Republicans held the governor’s mansion for the next 16 consecutive years.

Over this long period, the balance of the state’s congressional delegation remained highly competitive. Republicans controlled most seats early in the 1900s, and again during the 1920s, a decade of GOP dominance nationwide. Democrats rebounded to win most of California’s seats under Roosevelt and Truman, but Republicans in turn revived to take a majority during the sharp postwar backlash against Democrats in 1946. Republicans then held most of California’s House seats until 1958, another bad midterm for the party. The Democrats maintained their advantage over the next 15 years, but their edge was narrow until the GOP’s Watergate collapse in 1974.