It’s not unexpected that Pew Research’s new survey would find a wide ideological gulf between younger and older Americans. We’re by now used to the idea that younger voters lean Democratic and older ones Republican, though that association itself has not been uniform over time.

What’s perhaps unexpected is that younger voters keep moving left as older voters keep moving right. In 2006, 18 percent of millennials (those born between 1981 and 1998, under Pew’s definition) identified as liberal Democrats while 27 percent of the silent generation — pre-boomers, born 1928 to 1945 — identified as conservative Republicans. Those percentages have climbed. Now, 27 percent of millennials identify as liberal Democrats and 36 percent of the silent generation identifies as conservative Republican. (Younger voters are also much more likely to identify as independent.)

If we overlay that data onto the actual population, an interesting distribution results. Overall, there are more Democrats than Republicans, but there are more conservative Republicans than liberal Democrats. But only for now. Because younger people lean left, the distribution of political ideology is top-heavy to the upper-left. There are a lot more millennials than there are members of the silent generation, after all — but also still a lot of conservative baby boomer voters.

Notice that this isn’t precise; Pew’s data are in generational blocks, leading to some abrupt shifts were the generations meet. Still, it offers an interesting demonstration of how many Americans fit into each group.

To really understand American politics, though, that chart needs to be paired with the one below, showing turnout by year of age in the 2014 California general election. (Data for this was provided by Political Data in early 2015.)

2014 was an off-year election that tends to see stronger turnout from more reliable — older and wealthier — voters. But the curve doesn’t change much in shape during presidential years, just in slope. There are more young Democrats than old Republicans, but those old Republicans vote more.

Again, this isn’t new, but it raises the still-unanswered question: What happens as the population continues to age and those older voters die? Will Gen X and millennial voters stay Democratic? Will American politics shift to left? Will millennials remain less economically stable, and therefore less likely to vote?

Part of the reason that younger voters are more Democratic is that their generation is also more diverse. The two long-term trends the population will undergo over the next few decades is that the population will grow both older and less white, largely thanks to the country’s growing Hispanic population. How will that affect political views? How will the evolving parties

How will that affect political views? How will the parties evolve to accommodate the reshaped population — or will they?

I’ll update this article with answers in 2047.