Only a dozen black women have served as mayor of a major American city.
Baltimore has elected three in a row.
Sheila Dixon, Stephanie Rawlings-Blake and now Catherine E. Pugh are products of a system that has developed an unusual concentration of female leaders.
The pipeline starts at neighborhood association meetings, community cleanups and PTA events. It can lead to elected positions on the City Council and in the state's attorney's office, the comptroller's office and — for some — the city's top job.
"When you have a history of women's leadership it becomes normalized, but it really isn't normal," said Mileah Kromer, director of the Sarah T. Hughes Field Politics Center at Goucher College.
Kromer attributes Baltimore's run of black women mayors to the politics advanced by the Democrats who have long dominated city elections, and the idea that "representation begets representation."
"It's the 'If I can see it, I can be it' mentality," Kromer said.
Kelly Dittmar, a political scientist at Rutgers University, said Baltimore's "unique and distinct" record should be celebrated.
Dittmar co-wrote a report titled "The Status of Black Women in American Politics."
"It's a simple fairness factor: If we are meant to be a representative democracy, having folks who look like the folks they represent is important," Dittmar said. "Women of color guide public policy discussions based on their life experiences."
Glenn E. Bushel, chairman of the Baltimore City Republican Central Committee, said that while gender and racial diversity are laudable, too often diversity of political ideas is left behind in the city. Adopting more Republican ideas might help the city move forward in attempts to improve quality of life, he said.
"I don't see a lot of things getting better. … We certainly aren't creating jobs or improving housing," Bushel said.
African-American women have led the city since 2007, when then-City Council President Dixon succeeded Martin O'Malley as mayor.
Rawlings-Blake, Dixon's successor as council president, became mayor in 2010 after Dixon was convicted of embezzlement and resigned.
Pugh, a longtime state senator, defeated Dixon in the Democratic mayoral primary in April and won the general election in November to take office last month.
Among the 100 largest cities in the United States, Washington is the only other city to elect more than one black woman as mayor, according to the Center for American Women and Politics. No other major city has elected black female mayors consecutively.
Pugh said she is "honored to have been elected by the people to represent all of Baltimore."
"Baltimore has been one of those cities and Maryland has been one of those states that promotes equality and equity, and we show it politically and on the business level," she said. "It says a lot about Baltimore and its openness and its willingness to promote inclusiveness and diversity."
Baltimore's population of more than 620,000 is 63 percent black and 53 percent female.
Pugh is one of four black women currently serving as mayor of a large city. The others are Muriel Bowser of Washington, Ivy R. Taylor of San Antonio, Texas, and Paula Hicks-Hudson of Toledo, Ohio.
The first black woman elected mayor was Ellen Walker Craig-Jones in 1971 to lead Urbancrest, Ohio. Lottie Shackelford, who became mayor of Little Rock, Ark., in 1987, was the first elected to serve a large city.
In Baltimore and across the country, black women are an important voting bloc.
The majority of voters in Baltimore are Democratic, African-American and women, according to Annapolis-based pollster Steve Raabe. The state does not record the race or gender of voters, but demographic information can be determined based on exit polling, housing patterns and precinct-level turnout, said Raabe, president of OpinionWorks.
Democrats outnumber Republicans in Baltimore 10 to 1. African-Americans make up about 60 percent of registered Democrats, Raabe said. About 65 percent of the voters in the Democratic primary are women.
Baltimore voters have selected African-American women for several key offices.
Joan M. Pratt has served as comptroller since 1995. Two of the city's last three state's attorneys have been black women. Patricia C. Jessamy served for 15 years before she was ousted in 2010 by Gregg L. Bernstein. Marilyn J. Mosby beat Bernstein in 2014.
Two of the 15 members of the City Council are black women.
Shannon Sneed, a former television journalist who defeated incumbent Warren Branch in the Democratic primary, had long been active in community groups.
She said she ran for office because she was disappointed with the representation her family and neighbors received.
"I figured I was paying enough in taxes and that it had to be better," said Sneed, of Ellwood Park. After losing in her first council primary in 2011, Sneed joined Emerge Maryland, an organization that trains Democratic women to run for office.
Research shows women need more persuasion than men to run for public office, and black women are more likely than men or white women to be discouraged from running. Groups such as Emerge Maryland try to guide potential candidates over hurdles that block more from running.
Martha McKenna, president of the Emerge board, said black women play an important role in their families, communities and churches, and political involvement is a natural extension.
McKenna, who worked on Dixon's mayoral campaign this year, said both Dixon and Sneed, for example, took similar paths to office, albeit 30 years apart and from opposite sides of the city. "They are representatives of other African-American women in our city: They have taken very active roles in making neighborhoods safer," she said.
Among the members of Emerge's latest class is Robbyn Lewis, who was nominated recently to replace former Del. Pete Hammen in the House of Delegates. Hammen, who represented the 46th legislative district, joined Pugh's administration this month.
The gains of women in Baltimore come as the retirement of Sen. Barbara A. Mikulski leaves Maryland's congressional delegation without a woman for the first time in 46 years.
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Women hold less than a third of the 188 seats in the Maryland General Assembly. About 20 state lawmakers are black women.
On local councils and commissions across Maryland, women make up less than 15 percent of the elected leaders.
But in Baltimore, Kromer said, three consecutive black women mayors will encourage girls to one day run for office.
"For voters who grow up in the city, it is not a new normal — it is just normal," Kromer said. "These little girls will begin to assume leadership roles, and it will continue the pipeline."
Baltimore Sun reporter Pamela Wood contributed to this article.