Young people have historically voted in much lower numbers than older Americans, and 2016 was no exception. But their absence is most pronounced in elections at the local level. Disparities in turnout -- already vast in presidential and congressional elections -- are even greater in contests that decide who runs the nation’s cities.

A study conducted by Portland State University tallied voter turnout in the most recent mayoral elections in the 30 largest cities. It found that residents 65 years and older were a median of seven times more likely to vote than those ages 18 to 34, who frequently registered turnout rates in the single digits. “There’s an enormous disconnect with younger citizens in understanding the impact that local governments have,” says Phil Keisling, director of the university’s Center for Public Service. “They’re ceding to their grandparents the political decisions.”

A number of factors contribute to dismal youth participation. For starters, young people move a lot, making them less likely to be registered to vote or feel as vested in a city as longtime residents. They also tend to be renters, a demographic that doesn’t cast ballots as often as homeowners, even when they’ve lived longer in a particular place.

Keisling suspects that younger adults often fail to recognize the importance of mayors and city councils in addressing problems such as housing affordability and public safety. Or, if they do make the connection, they may not think anything will be done about them. The end result, Keisling says, is that politicians spend much more time listening to the concerns of older residents -- the constituency that’s most likely to elect them to office.

Consider Las Vegas, where less than 2 percent of registered voters between the ages of 18 and 34 voted in the city’s 2015 mayoral election, compared to about 33 percent for those 65 and over. Local officials there just tend to target their efforts on older voters, says David Damore, a political science professor at the University of Nevada, Las Vegas.

The vast majority of big-city mayoral elections analyzed by Portland State didn’t coincide with presidential or midterm campaigns, in which turnout is higher. Experts contend that the lower the voter turnout overall, the greater the participation gap between younger and older voters.

For the study, researchers analyzed voter registration records for what they considered to be the most important election in each city, typically either the last runoff, or, in jurisdictions with one-party control, the primary election. In over half of the big-city mayoral elections reviewed, fewer than 1 in 10 registered voters ages 18 to 34 showed up to vote. Age disparities are even greater when studies examine participation for all citizens, including those not registered. Often-cited exit polls and Census survey estimates understate the true disparities, according to Keisling.

Some cities with the biggest age disparity in turnout, such as Dallas and Miami, didn’t hold very competitive elections during the period studied. But even in Houston, which elected a new mayor in 2015 in a close contest, turnout for registered voters ages 18 to 34 (6.6 percent) was more than six times lower than for those 65 and up (42.9 percent).

In general, the age gap is smallest in local voting that coincides with national elections. But occasionally a stand-alone local contest will rally younger voters. In San Francisco’s 2015 mayoral election, 28 percent of registered voters ages 18 to 34 participated in the balloting that gave Mayor Ed Lee a second full term. Turnout likely benefited from two ballot measures of particular interest to millennial renters: an affordable housing bond question and a proposal that would have restricted Airbnb and other short-term housing rentals. The city’s population of young adults is also better educated than in most big cities, another reliable predictor of voting participation.

Jurisdictions with larger immigrant populations usually have smaller age disparities in turnout, according to University of California, Berkeley professor Laura Stoker. That’s mostly because first-generation U.S. citizens participate at lower rates even in their later years.

It’s widely agreed that the generational voting divide is a problem for the democratic process, but it’s not clear what can be done about it. Some advocate holding local elections to coincide with state contests to boost turnout. Keisling suggests that, where voting takes place over a period of several weeks, as in Oregon, cities could report real-time data showing turnout by neighborhood, age group and other demographics. Publicizing turnout, he says, could potentially motivate more underrepresented groups to come to the polls.

But these simple fixes alone aren’t likely to make much headway against a complex societal habit. Young people often feel disconnected from their neighborhoods, and research has shown that the disconnected are less apt to vote. “Young people are plugged into more national movements and issues based on their friends and interests,” says Kei Kawashima-Ginsberg, director of the Center for Information and Research on Civic Learning and Engagement at Tufts University.

While political groups and campaigns invest in youth voter outreach in state and national elections, this sort of activity is often nonexistent at the local level. Kawashima-Ginsberg says cities should step up to build pipelines for young people to participate in civic life. “When the cities and school districts make community service and internships in government really part of routine school life,” she says, “you end up getting people who are prepared to work and have a deep understanding and belonging to the city.”

A study published in the American Educational Research Journal in 2007 linked volunteering in high school to increased voter turnout. Performing high school community service, either voluntary or required, was found to be a statistically significant predictor of future participation in local elections.

In Hampton, Va., teenagers are appointed to a civic youth commission where they learn about government, help with outreach efforts and offer policy guidance on issues pertinent to them. For one recent project, members organized bus tours introducing their peers to the city’s transportation system. Earlier this year, they held a youth-focused candidate forum followed by a mock vote. Other jurisdictions have launched their own initiatives, such as one in Boston that allows young people to participate in budget exercises.

Two Maryland municipalities, Takoma Park and Hyattsville, lowered the voting age to 16 in recent years for local elections. The idea was that if 16- and 17-year-olds could vote while still living with their parents or studying civics in high school, they would be more likely to go to the polls the first time out, and continue doing so throughout their lives. This past November, San Francisco narrowly rejected a measure to lower the voting age to 16 for local elections, but nearby Berkeley approved a similar measure.