Bill de Blasio poses with his family, wife Chirlane McCray, son Dante de Blasio and daughter Chiara de Blasio after voting at a public library branch on Election Day on November 5. 
Strangers stared at them on the street. The motel front-desk clerk couldn't grasp they were a couple. A passerby mistook their child as adopted.
The relationship between Bill de Blasio, who is white, and Chirlane McCray, who is black, was once a spectacle even on the multiethnic streets of New York City. Now, that relationship has helped propel Mr. de Blasio into City Hall, and put the couple and their two children among the nation's most prominent interracial families, a symbol of changing attitudes.
"It's fair to say we represent something that is changing in our society," said Mr. de Blasio, 52 years old, sitting next to Ms. McCray at a Brooklyn bar waiting for a plate of french fries to arrive. "We hope that maybe we're a positive example."
Bill de Blasio with son Dante, daughter Chiara and wife Chirlane McCray. 
Mr. de Blasio's family played a crucial role in his campaign for mayor, a vivid representation of ethnic harmony in a city where there have long been racial tensions. Many credit a TV ad this summer that featured the couple's 16-year-old son, Dante, who sports an eye-catching Afro, with catapulting Mr. de Blasio to a win in the Democratic primary.
For Mr. de Blasio—a sometimes wonkish liberal who has worked most of his life in politics—his family showed that he isn't "some boring white guy," as his daughter Chiara, 18, said to laughs at a fundraiser this year.
Mr. de Blasio's use of his family faced fire from Republican nominee Joe Lhota, who said: "This is a campaign about the future of our city, not about your children." But Ms. McCray said it showed a side of her husband the public should see. "It gave him more dimension," she said. "I think we help show what Bill cares about."
The de Blasios are poised to occupy Gracie Mansion as the number of interracial marriages is growing. Roughly 15% of new marriages nationwide in 2010 were between spouses of different races or ethnicities, more than double the share in 1980, according to a report published in 2012 by the Pew Research Center. In the city, 14.3% of marriages in 2010 were interracial.
Black and white couples remain rare, though, comprising less than 3% of New York marriages. Barriers to interracial marriage exist even 46 years after the U.S. Supreme Court struck down anti-miscegenation laws in 1967, said Michael Rosenfeld, an associate professor of sociology at Stanford University. "Race is still actually the strongest division in the marriage market, stronger than religion, stronger than class, stronger than education," he said.
The de Blasios, Mr. Rosenfeld said, are "in a unique position to pave the way toward a more post-racial America."
Mr. de Blasio and Ms. McCray met in 1991 at City Hall while they were both working for David Dinkins, the city's first and only black mayor. It was a sensitive time for an interracial couple—just after tensions between blacks and Hasidic Jews in Brooklyn's Crown Heights neighborhood exploded into riots. It was also the year of the release of "Jungle Fever," the Spike Lee movie about a black man dating a white woman.
They attracted attention. "Classic situation, we go into a store, we go into a restaurant, whatever, and the assumption of the people working there was that we weren't together," Mr. de Blasio said. "That would be a constant."
Early in their relationship, they were taunted on the subway. Teenagers yelled "Jungle Fever" at them. It was unsettling, they said, harder to shrug off than it would be today.
Once, when checking into a motel, a clerk couldn't grasp that they were together. "It literally, like, couldn't compute for this guy," Mr. de Blasio said.
Ms. McCray said she didn't feel comfortable with Mr. de Blasio picking her up in Flatbush, the largely African-American neighborhood in Brooklyn where she lived. "There was a lot of staring—unsubtle staring," Mr. de Blasio said.
He said he doesn't believe most people meant harm. Even his mother, Maria, a liberal Democrat, was opposed.
"At the wedding, she said to one of my friends, 'You know, I'm not very happy about this wedding,'" Ms. McCray said.
Mr. de Blasio said his mother's "better angels prevailed" when their elder child, Chiara was born. By the time his mother died in 2007, he said, she considered Ms. McCray to be the daughter she never had.
Ms. McCray said her family was more receptive to Mr. de Blasio at first and had a history with interracial marriages: Ms. McCray's maternal grandmother—"the only grandmother I ever knew"—was white.
The couple settled in Park Slope, a Brooklyn neighborhood where they felt accepted. But even then, there were challenges. Ms. McCray recalled coming out of a bank with Chiara in a stroller "and this woman said, 'Is she adopted?'"
"There were times when I know that people didn't know if I was the nanny or the mom," Ms. McCray said.
Mr. de Blasio said he had similar moments with his children. "People had trouble figuring out who was with who and why and how," he said.
Laura Hart, a close friend, said she believes having an interracial family in Gracie Mansion "will have resonance."
"It will shift the way New York is viewed nationally and I think globally," she said. "It shows the diversity and the tolerance and the openness of New York for a family like Bill and Chirlane's representing it."
Mr. de Blasio and Ms. McCray said they hope their family becomes a positive example of interracial families, which she said aren't featured on television. When they are, such as in a recent Cheerios commercial, they still get singled out for criticism.
Still, Ms. McCray said, "I hate even the word interracial, because we're one race: We're human."

What a lovely family