U.S. House Minority Leader Nancy Pelosi (D-Calif.) speaks to reporters about the potential for a U.S. government shutdown, alongside House Minority Whip Steny Hoyer (D-Md.), left, and Reps. Peter Welch (D-Vt.) and James Clyburn (D-S.C.) at the U.S. Capitol in Washington on Sept. 25, 2013. (Jason Reed/Reuters)

In America, Republicans are increasingly the party of older Americans. But in Congress, that's still the Democrats.

Democrats just added the youngest member of leadership in Congress, with 42-year-old Rep. Ben Ray Lujan (D-N.M.) being tapped as chairman of the Democratic Congressional Campaign Committee. Despite this, they still have a far older leadership team than Republicans. By more than a decade, on average.

The average age of the top five House Democrats (including the party chairman as No. 5) is now 64.2 years old, down slightly from 65 last Congress, as compared to 53 for the top five House Republicans.

And Lujan and 56-year-old House Democratic Caucus Chairman Xavier Becerra (D-Calif.) bring that average age down quite a bit. Because aside from them, the top three House Democrats — Nancy Pelosi (D-Calif.), Steny Hoyer (D-Md.) and Jim Clyburn (D-S.C.) — are three of the four oldest leaders in Congress.

Part of the reason Democratic leaders are older, though, is that their conference is older. A Wall Street Journal analysis in 2011 showed that House Democrats, on average, were more than five years older than House Republicans. (These are old numbers, so it's not apples-to-apples, but they are probably close to where things stand today, given that Democrats added some seats in the 2012 election and the GOP added some in 2014.)

Five years doesn't sound like a lot, but across hundreds of members of Congress, it's a significant difference. And it's a big reason that Democratic leaders are considerably older three years hence.

Below, we compared the average age of the top five leaders in each chamber for each party, and also showed the average age of their members (again, circa 2011, not today). You'll notice that Democrats have older memberships in both chambers, along with older leadership.

You'll also notice that House Democrats are significantly older than House Republicans, but they're about on-par with Senate members from both parties. The Senate does skew a little bit older historically, but the numbers suggest, as much as anything, that the House GOP caucus is considerably younger.

All of these things are cyclical, of course, and when Pelosi, Hoyer and Clyburn step down, they'll likely be replaced by much younger members such as Becerra or maybe Lujan, or 55-year-old Chris Van Hollen (D-Md.).

But for now, Pelosi seems to be content to stick around for a while. And given her fundraising prowess, it's hard to see Democrats supplanting her. Which suggests that the youth movement will remain in waiting.