Chicago Mayor-elect Lori Lightfoot speaks to supporters on election night Tuesday.
CNN  — 

When Lori Lightfoot was elected Tuesday as Chicago’s first black woman mayor, she joined a small but swelling sisterhood.

Of the 307 US cities with a population of at least 100,000, 13 now have African-American female mayors.

That isn’t many – about 4%. But their numbers, while modest, have spiked in recent years.

In 2015 there was a mini-wave of mayoral elections ushering black women into office in San Antonio, Washington and other large cities. Of the 19 black women in history who have served as mayors of the largest 100 US cities, half are currently in office, according to the Center for American Women and Politics (CAWP).

Black women officeholders, on both a national and local level, are becoming less of a rarity, said Kelly Dittmar, a CAWP researcher.

“Women have done the work for a long time and have the experiences to establish themselves,” she told CNN.

In the last two years black female mayors have been elected in such major metropolises as Atlanta, Charlotte, New Orleans and San Francisco (see map above).

New Haven Mayor Toni Harp, president of the African-American Mayors Association, says black female politicians have been inspired by strong mothers, aunts and other women in their community.

“Why can’t we do it on behalf of ourselves and our visions?” she told CNN. “Women can do this job. African-American women can do this job.”