As a dramatic election night unfolded Tuesday in Virginia, municipalities in the nearby Maryland suburbs held elections that came with their own share of surprises.

In Rockville, officials saw record turnout in the state’s first vote-by-mail election, where incumbent Mayor Bridget Donnell Newton triumphed over challenger Virginia Onley in a contest that focused on development and affordable housing.

In Bowie, residents elected the city’s first black mayor, while in Greenbelt, a 27-year-old with a history of civic activism seemed poised to take over leadership from an incumbent mayor and veteran City Council member.

Rockville’s election was closely watched by officials within and beyond the county because of its reliance on the mailbox rather than the ballot box — a shift that has taken hold in West Coast states including Oregon and Washington but is still rare along the East Coast.

More than 12,200 ballots were cast this year, vs. 6,468 in 2015, Rockville announced Wednesday. This represents about 28 percent of the city’s 44,000 registered voters, exceeding the Board of Supervisors of Elections’ stated goal of 20 percent participation.

Residents said Wednesday that they approved of the new system, though some had concerns about cost. According to Rockville officials, this year’s municipal elections cost $350,350 — more than five times the cost of the 2015 election.

Further north in Montgomery County, in Gaithersburg, unofficial election results show that incumbent City Council members Neil Harris, Ryan Spiegel and Robert Wu were all reelected to four-year terms.

In neighboring Prince George’s County, Timothy Adams will succeed longtime Bowie Mayor G. Frederick Robinson. Adams defeated two opponents: 22-year council member Dennis Brady and Annapolis lobbyist Leonard Lucchi, who had the endorsement of a host of politicians, including Robinson.

Adams, a disabilities advocate and business owner, shored up support among liberals and young voters in this election, which followed his unsuccessful bid for state Senate last year. He will lead a jurisdiction of 60,000 that has transformed in the past 50 years from a predominantly white bedroom community into a diverse city that is 53 percent black.

Voters elected incumbent Henri Gardner and newcomer Ingrid Harrison for at-large seats on the Bowie City Council; along with incumbent Michael Esteve for District 1; incumbent Dufour Woolfley for District 2; Adrian Boafo for District 3 and Roxy Ndebumadu for District 4.

Concerns over development and density featured heavily in the lead-up to Tuesday’s races. In Bowie, Adams argued that lobbyists and developers have had too much impact on the city’s growth.

In Rockville, Newton, who will serve her third term as mayor, argued for “managing growth” in the city of 67,000. Onley, a former City Council member, had campaigned for greater density in downtown Rockville and cited affordable housing as a top ­priority.

“The key difference between the two candidates is that one side was pro-development and the other wanted to manage growth,” said Michael Dutka, a scientist who contributed to Greater Greater Washington’s endorsement of Onley and her slate of candidates, who ran under the banner “Team Rockville.”

Dutka, a self-described “YIMBY” (which stands for Yes, In My Backyard), said he was disappointed with the election results.

Newton argued that her position on housing had been mischaracterized.

“I’m not anti-affordable housing. I have never been,” she said in an interview. “I just think we need to have a conversation on what kind of affordable housing we want. . . . Our neighborhoods need to be front and center in these conversations.”

Two candidates on “Team Rockville,” Mark Pierzchala and newcomer David Myles, won council seats. They are joined by incumbent Beryl Feinberg and newcomer Monique Ashton, who both ran as part of Newton’s slate, “Rockville Forward.”

In Greenbelt, 27-year-old Colin Byrd received more votes than incumbent Mayor Emmett V. Jordan, meaning Byrd will probably be elevated from council member to mayor by his council colleagues when the new term begins.

Byrd, a Greenbelt native, spearheaded efforts as a student at the University of Maryland at College Park to remove the name of segregationist Harry C. “Curley” Byrd from the school’s stadium. He has also filed complaints about alleged ethics and open-meeting violations committed by Maryland politicians over the years.

Jordan received enough votes to retain a seat on the Greenbelt City Council, as did incumbents Judith Davis, Silke Pope, Leta Mach, Edward Putens and Rodney Roberts.

In Laurel, the second-largest municipality in Prince George’s, Mayor Craig Moe was reelected. Incumbent City Council members Carl DeWalt and Michael R. Leszcz, who had served at large, won new terms in Ward 1, along with colleague Keith Sydnor and newcomer Brencis Smith in Ward 2. Valerie Nicholas, who had served in Ward 1, was elected to an at-large council seat.

College Park Mayor Patrick Wojahn also won reelection, along with incumbent City Council members S. M. Fazlul Kabir, Catherine Kennedy, P.J. Brennan, Monroe Dennis, John B. Rigg, Robert Day and Denise C. Mitchell. Newcomer Maria Mackie will replace outgoing council member Dustyn Kujawa.