One way of looking at last week’s midterm results is as a national mood swing, made up of irrational fear (Ebola, the terrorist next door), anxiety about the economy, and, perhaps above all, a vague, very real dissatisfaction with President Obama, stemming in part from a wish that he’d do something, as if a President has the power to do very much about ordinary problems that affect us all. (“Mr. President, can you get me raise?”)

But, for students of election charts, it was not a major mood swing. It certainly couldn’t compare to the great overturn of 1946, when Republicans, after fourteen years of Democratic dominance, got to use a terrific slogan: “Had enough?” Nor can it rank with 1958, when the Eisenhower Presidency, and Dwight D. Eisenhower himself, seemed to be in steep decline, and the nation was in recession. That year, Republican professionals seemed most worried about a scandal that voters probably didn’t care about: Ike’s chief of staff, Sherman Adams, had accepted unseemly gifts, including an oriental rug and a vicuña coat.

These mood swings may not have much predictive value when it comes to Presidential years. In 1946, Harry Truman seemed done for. He had become President just twenty months earlier, following the death of Franklin D. Roosevelt, and was widely considered to be a nonentity, a placeholder, constitutionally forced to stay put until the Republicans could take back the White House. (Another slogan that year was “To Err Is Truman.”) He was kicked around in a way that makes today’s critics of Obama seem gentle. Major newspaper columnists, who had a lot more influence than the people who populate today’s op-ed pages, could be merciless, starting with Walter Lippmann, the primus inter pares of opinion writers, who called the men (there were no women) who surrounded Truman “blunt trash” who did “not have the brains, and practicality, none of the wisdom from experience and education to help the President.” Before the 1946 midterm vote, J. William Fulbright, then a freshman senator from Arkansas, suggested that Truman could help things along by appointing a Republican secretary of state (the post then next in line of succession when there was no Vice-President) and resigning. Truman’s response was to call Fulbright “an overeducated Oxford S.O.B.”

As it turned out, Democratic fears about 1946 were entirely justified. Republicans gained fifty-five seats in the House and twelve in the Senate, a congressional takeover even more impressive when one remembers that there were just forty-eight states at the time. Democrats, in a state of panic, began casting about for a Presidential candidate to replace the hapless Truman. In a sign of desperation, Americans for Democratic Action, the liberal wing of the Party, tried to recruit a candidate who had not yet made his political affiliations known: General Eisenhower.

And yet in 1948, with not much changed in the way of economic circumstances or tensions with Stalin’s Russia—or in Truman himself—there was another national mood swing. Not only did Truman defeat Thomas E. Dewey, the off-putting governor of New York, but the Democrats took back the House and the Senate. Who would have thought?

In the 1958 midterms, after six Republican years, with a recession affecting the outlook of voters and the made-in-Russia Sputnik, the world’s first artificial satellite, circling the Earth, the G.O.P. experienced much of what the Democrats had gone through in 1946—they lost forty-seven seats in the House and thirteen in the Senate. What happened next shows that swings, as reliably as they may arrive, come in many forms. The Democrats won the White House two years later, when Senator John F. Kennedy defeated Vice-President Richard Nixon, by the narrowest of margins; the Republicans picked up one Senate seat and forty-seven House seats.

Democrats, although they may dream of fable-like narratives to rival the Truman upset in 1948, have a lot more to worry about than this year’s relatively modest Republican comeback, which ended with a gain of twelve seats in the House and seven in the Senate. As the Washington Post’s Dan Balz recently suggested, the midterm elections of 2010 and 2014 have “hollowed out” the Party, by which he means that a number of talented politicians who might have had impressive futures, such as Michelle Nunn, who had been given a good chance to win a Senate seat in Georgia, were defeated. It’s a generational thing: the sort of turnover that brought people like Kennedy and Nixon to Congress in 1946 seems to be missing in 2014. While the midterms may have had no perceptible effect on a potentially large Republican field (including such “formerlys” as Mitt Romney and Jeb Bush and such appalling office holders as Ted Cruz), it’s been widely noted that the Democrat who seems to have benefited most is Hillary Clinton, already the presumptive front-runner and now, in many ways, a party of one. Certainly, as Ryan Lizza has pointed out, front-runners are vulnerable to insurgent challenges, but they mostly tend to remain front-runners.

So have we just seen 1946 or 1958? In one sense, Hillary Clinton is in a position similar to the front-running Richard Nixon as he headed into 1960, after the midterms helped to flatten his party with the defeat of possible rivals, such as William Knowland, who lost his bid to become California’s Governor.* The only serious potential challenger left standing was Nelson Rockefeller, who had just been been elected to his first term as governor of New York; he turned out to be far too hesitant to fight for the nomination in a party that has never had much of an appetite for insurgency.

That’s not to say that Hillary Clinton, like Richard Nixon, would lose a general election, but when faces and personalities become too familiar voters tend to tune them out. This phenomenon has certainly contributed to the discontent with President Obama, and gives hope to such potential insurgents as former Senator Jim Webb, who seems more willing than most politicians to take on issues such as mass incarceration. (“If you have been in prison, God help you if you want to really rebuild your life,” Webb told Lizza.) When the post-Truman Republicans were ready to try again for the White House, in 1952, the favorite of the Party’s Old Guard was the conservative Ohio senator Robert A. Taft; the faction that propelled Eisenhower to the nomination understood that Republicans needed a fresh way to look at the world. The same may be true for Democrats in 2016: to paraphrase Bill Clinton, if you want to build a bridge to the rest of the twenty-first century, it may be time to look for a new set of blueprints.

*Correction: This sentence has been amended to clarify that Knowland was not the incumbent.