After the March 7 story about the changing roles of the District’s young voters and African American voters, some readers asked for more background about voter registration and turnout.

Paul Schwartzman’s story, based on a Post analysis of voting data, focused on two notable developments in the November general election.

The first: Voters ages 25 to 34 came to outnumber senior citizens, who traditionally have been the largest D.C. voter age group.

A graphic showed how the number of young voters doubled since the last election, surging past senior voters, who voted in about the same numbers as in 2010.

Another version of that graphic shows total voter registration figures added to the number of voters for each age group.

It’s clear that young people dominated the voter registration rolls even in 2010. But they ended up being one of the smallest voting groups because so many didn’t vote.

While young registration continued to grow for 2014, much of their surge also came from a turnout rate that jumped from 21 percent to 31 percent.

Senior voters, meanwhile, improved their turnout by seven percentage points to 53 percent. But with declining registration, the number of voters remained about the same as in 2014, and young voters jumped ahead.

The second development from November: Voters from African American neighborhoods lost their long-held majority among voters.

Voter registration estimates by race don’t suggest that registration numbers were a key factor. Blacks accounted for about 51 percent of those registered in November, down only about half a percentage point from four years earlier.

A greater factor was a widening difference between how likely blacks were to vote compared to others. Overall, after years of decline, turnout in the District rebounded in 2014 to 39 percent, the best since 1998. That likely reflects a November ballot that included a marijuana referendum, as well as a mayoral race for open seat.

That change was uneven across the city. Among black voters, estimates for turnout jumped by five percentage points, to about 35 percent. But among other voters, turnout jumped twice as much, by 10 percentage points. That wider turnout gap resulting in the black share of the electorate slipping below 50 percent for the first time in years.

Will these changes last?

For young voters, some might imagine that such a surprising turnout surge could reflect a fickleness that leads next time to a surprising turnout collapse. But because of their high registration numbers, young voters in the future will be a more tempting target for those seeking votes.

For black voters, it’s important to keep in mind that these and all estimates of their voting are estimates. Voter data for the District doesn’t include race. The Post used 2010 U.S. Census data for neighborhoods to estimate for the racial makeup of each precinct and its voters. Despite demographic trends showing a long, slow decline in the African American share of the District’s population, they still make up about half of eligible voters.