(Matt McClain/The Washington Post)

A recent round of surveys has underscored young Americans' low level of interest in the coming midterm elections. Just over one-third of Americans ages 18 to 29 said they were “certain” to vote, a sharp contrast with the 81 percent of the 65-plus crowd who said the same thing. A separate survey found that more than half of registered voters ages 18 to 29 said they knew little or nothing about congressional candidates running in their district, with a similar percentage saying that “it doesn’t really matter” which party ultimately wins control of Congress.

These aren’t exactly new developments. Turnout data compiled by political scientist Michael McDonald shows that the youngest voters have long been the group least likely to head to the polls, a trend going back to at least the 1980s.

Young voters' disengagement grabs headlines every election cycle, in part because it’s somewhat shocking to the older and more civically minded among us. But McDonald’s data also shows evidence of a trend that’s flown largely under the radar in recent years — declining electoral engagement among middle-aged voters.

(Washington Post Illustration by Christopher Ingraham/Washington Post Illustration by Christopher Ingraham)

The chart above, which shows turnout rates by age group for midterm elections since 1986, tells the story. McDonald compiled those numbers by correcting self-reported turnout rates from the Census Bureau’s Current Population Survey.

Between 1986 and 2014, turnout dropped by seven percentage points among 45-to-59-year-olds and by nine percentage points among 30-to-44-year-olds. Turnout fell by five percentage points among the youngest cohort, while it actually rose by a percentage point among voters 60 and over.

While decline among the young is a real trend, the middle-aged aren’t voting as they used to, either. As a result, the age composition of the electorate has shifted significantly since the 1980s. In 1986, for instance, 30-to 44-year-olds made up the largest share of the electorate, at 31 percent. In 2014, their share had fallen to 20 percent.

(Washington Post Illustration by Christopher Ingraham/Washington Post Illustration by Christopher Ingraham)

The 60-plus age group, however, increased its share from 30 percent of voters to 39 percent over that period. Meanwhile, the 45-to-59-year-old age group grew by six percentage points, while the youngest cohort shrunk by an identical amount.

Some of this change is a function of underlying demographic trends, such as the aging of the baby boomers. But shifting turnout trends are also radically altering the face of the electorate, especially in midterm election years. If we assume that turnout rates by age in 2018 will be similar to what they were in 2014, here’s what will happen:

  • The youngest voters, who make up 21 percent of the total voting-age population, will cast just 10 percent of the ballots, effectively halving their electoral clout.
  • Voters 30 to 44 will be underrepresented by about five percentage points relative to their share of the voting-age population, while those between 45 and 59 will be overrepresented by a similar amount.
  • The oldest voters, 60-plus, will cast nearly 4 in 10 midterm ballots, despite making up just 28 percent of the midterm electorate.

The end result, as it almost always is during midterm years, will be a Congress that disproportionately represents the interests of the elderly relative to the interests of the young.

To be sure, there are some structural issues at play here. Republican lawmakers in particular have shown a keen interest in recent years in policies that make voting more difficult or less representative. It’s also more difficult for people who are young and just getting started in their careers and families to find time to vote.

But at the end of the day, the most significant barrier to most potential voters' participation in elections is apathy. “I’m not into politics,” as one college student succinctly put it in a recent Washington Post story on why people don’t vote.

As the trends above show, 30-, 40- and 50-somethings are increasingly not into it. either.