CNN
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Democrats have done a lot better in the midterm elections than a lot of pundits and analysts had anticipated. They’re favored to hold on to the Senate and look to have kept their losses in the House to a minimum.

In doing so, Democrats have defied historical precedent, which suggests the president’s party loses significant ground in midterm elections.

President Joe Biden credited, in part, “historic” turnout by younger Americans for the strong Democratic performance.

A look at the data suggests there probably wasn’t a surge of youth participation relative to the rest of the electorate. But it does suggest that Democrats defied election expectations this year because of a historically large age gap that saw young voters overwhelmingly back Democratic candidates.

The lack of a youth surge becomes quickly apparent when you look at the exit polls. Voters under the age of 30 made up 12% of all voters. In every midterm in the last 20 years, this group has made up between 11% and 13% of the electorate.

(Other data, too, shows that younger voters did not make up a significantly larger portion of the electorate compared with prior midterms.)

Now, overall turnout is likely to be higher this year compared with most past midterms. It could therefore be argued that young voters did turn out in larger numbers than they have historically, but that is true of every age group.

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While they may not have made up a larger share of the electorate than normal, young voters still made their presence felt.

Democrats would have gotten crushed without young voter support. Democratic House candidates won voters under the age of 45 by 13 points, while losing voters age 45 and older by 10 points.

Breaking it down further, House Democratic candidates won voters under 30 by 28 points – that’s an increase from their 26-point edge with this group two years ago.

This is significantly different from other age groups, the exit polls show. Democrats lost every age slice of the electorate 45 years and older by at least 7 points, including a 12-point loss among senior citizens (age 65 and older).

What is perhaps especially interesting is that voters under 30 seemed to vote significantly more Democratic than those aged 30 to 39. Voters under 30 are partially Generation Z (those born after 1996) and partially the youngest millennials. Voters between 30 and 39 are the oldest millennials.

These older millennials were the strongest supporters of Barack Obama during his 2008 primary campaign and eventual ascendency to the presidency. This year, they backed Democratic House candidates by only 11 points.

Notably, today’s Democratic Party relies on the youngest of voters in a way that it historically hadn’t – at least not until the last few elections.

Consider the first midterm (2006) when millennials made up a significant share of voters under 30. Democrats won 60% of their vote, which isn’t all that different from the 63% of voters under 30 they won this year.

Remember, though, that Democrats easily won the House popular vote in 2006, while they’ll probably lose it by a couple of points this year. In fact, Democrats won every age group (under 30, 30-44, 45-65 and 65+) in the 2006 midterms. The difference in support for Democratic House candidates in 2006 between voters under 30 (60%) and those 65 and older (49%) was 11 points.

This year that gap was 20 points (63% versus 43%).

Going further back to 1990 (the last midterm when none of today’s voters under 30 were alive), there was basically no age gap. A similar percentage of voters under 30 and those 65 and older cast ballots for Democratic House candidates (52% and 53% respectively).

When you look at these changes, you can see why Biden was so eager to praise young voters. He’s absolutely right that they’re a vital part of the Democratic coalition. Tuesday’s result, though, wasn’t because they showed up in larger numbers. It’s because those who did show up were so Democratic.