Boston voters are heading to the polls Tuesday not only to choose between Democrats Michelle Wu and Annissa Essaibi George for mayor, but to mark a turning point in the city's history, for the first time electing a woman and person of color to helm Boston.

The choice of Wu and Essaibi George for the top political post is just the latest marker of how much the Boston of not-so-long-ago — known for its ethnic neighborhoods, glad-handing politicians and mayors with Irish surnames — is giving way to a new Boston.

Throughout its long history, Boston has previously only elected white men as mayor.

Despite the groundbreaking nature of the candidates, the campaign has turned on familiar themes for the city's 675,000 residents, including public education, policing, public transportation and the skyrocketing cost of housing.

Among the newer issues facing Boston residents is the effect of climate change on the costal metropolis.

One of the thorniest issues in the campaign is whether Boston should pursue a form of rent control or rent stabilization, something supported by Wu and opposed by Essaibi George. In 1994, Massachusetts voters narrowly approved a 1994 ballot question banning rent control statewide.

Both candidates have spent the final hours of the campaign urging their voters to get to the polls.

Nearly 40,000 ballots have already been cast in early voting. Democratic Secretary of the Commonwealth William Galvin told reporters Monday he estimates about 135,000 ballots will be cast in Boston — about 30% of the city's 442,000 registered voters.

Both candidates are children of immigrants.

The 36-year-old Wu, whose parents immigrated to the U.S. from Taiwan, grew up in Chicago and moved to Boston to attend Harvard University and Harvard Law School.

Essaibi George, 47, a lifelong Boston resident and former public school teacher, describes herself as a first-generation Arab-Polish American. Her father was a Muslim immigrant from Tunisia. Her mother, a Catholic, immigrated from Poland.

The contest could also be a test of whether voters in a city long dominated by parochial neighborhood politics are ready to tap someone not born and raised in the city like Wu, who grew up in Chicago.

Both Essaibi George and Wu are at-large members of the Boston City Council.

Wu was first elected in 2013 at age 28, becoming the first Asian American woman to serve on the council. In 2016, she became the first woman of color to serve as president. Essaibi George was first elected to the council in 2015.

The candidates reflect an increasingly diverse Boston.

The latest U.S. Census statistics show Boston residents who identify as white make up 44.6% of the population compared to Black residents (19.1%), Latino residents (18.7%) and residents of Asian descent (11.2%).

The city's previous elected mayor — Democrat Marty Walsh — stepped down earlier this year to become U.S. Secretary of Labor under President Joe Biden. Walsh was replaced on an acting basis by Kim Janey, sworn in March 24 as Boston's first female and first Black mayor.