Boston Housing Authority chief Bill McGonagle, the city’s landlord, takes his leave

After 40 years with the Boston Housing Authority, administrator Bill McGonagle, 67, is retiring.Craig F. Walker/Globe Staff/Globe Staff

Bill McGonagle had agreed to serve on the front lines of the city’s project to integrate public housing in South Boston and Charlestown in the late 1980s, but he didn’t know that assignment would hit so close to home.

He was executive assistant to Boston Housing Authority administrator Doris Bunte, tasked with helping to manage the desegregation effort, when shots were fired into his clearly marked city car parked outside his house on Dorchester Street in Southie. As he recalls, he had been quoted in the Globe that morning saying the BHA would not be deterred by threats of violence. The shots were an unmistakable message that his work to settle families of color into white neighborhoods wasn’t universally appreciated.

“My three kids were at the breakfast table with my wife when that happened,” he said last week. “And my kids were babies then, little tykes.”

Now McGonagle, 67, is stepping down as the head of the BHA, after 40 years with the agency, including the past decade as its head. He departs with a well-deserved reputation as one of the most passionate champions of poor people in city government.

At the time he took on the job as point person in integrating public housing, the city was still reeling from the battles over court-ordered school desegregation. Not only did South Boston and Charlestown have virtually no residents of color, black people didn’t even feel comfortable walking down the streets there.

The idea of moving black and brown families into the most hostile territory in the city — the very neighborhoods that had been powder kegs during the busing crisis of the 1970s — seemed like a recipe for disaster. At the same time, denying them access to the city’s biggest public housing developments — which had been unspoken policy — was blatantly discriminatory.

After a lawsuit by the NAACP, the city agreed to take the first steps toward integrating public housing.

As a lifelong resident of South Boston who had grown up in the Mary Ellen McCormack housing development, McGonagle was an obvious choice to serve as a liaison between the Boston Housing Authority and the residents of the projects that were being integrated. But “obvious’’ should not be confused with “easy.”

Successfully integrating South Boston and Charlestown was a key moment in the city’s racial history, and McGonagle played a huge role. But he gives much of the credit to others.

“The real heroes of that integration effort were the Bessie Paynes, the Liz Clinkscales, and the families of color that moved into those communities back in those days,” McGonagle said, reeling off the names of early integration pioneers in Boston.

In a field where every election results in turnover, careers like McGonagle’s have become rare. He started at the BHA as a custodian; he has to be the last department head who served in the Flynn administration.

But his achievements are about far more than longevity. “When I became mayor, I asked him to stay on because he produced results, and the residents love him,” Mayor Martin J. Walsh said. “He cares about poor people, and he cares about helping people. Every development you go to, the tenants just love him.”

The BHA houses 25,000 tenants in developments across the city and provides subsidies for about 25,000 more. Some 98 percent of its units are occupied, which reflects the high demand for them. The annual income of BHA residents is just $15,000 a year. In effect, the BHA administrator is the landlord for Boston’s poorest residents.

As demand for housing has remained intense, aid from the federal government has sharply declined. That has gotten worse in the Trump years, but federal aid for low-income housing has been insufficient for years.

That reality has transformed McGonagle’s job. Preserving affordability and maintaining some of the nation’s oldest housing developments have forced him to become a developer. The city’s biggest housing projects, including Bunker Hill, Bromley Heath (now known as the Mildred C. Hailey Apartments), and his beloved Mary Ellen McCormack have been or will be completely renovated, through public-private partnerships that will combine public housing with market-rate housing, a project that will take at least a decade to complete.

In effect, affluent people eager to move into desirable properties will subsidize the housing of their low-income neighbors. It’s an ingenious way to renovate old housing that won’t survive another generation without it.

People who are leaving high-profile jobs always say they’re going to spend more time with their families, but McGonagle really means it. His five grandchildren have active lives, and he’s not about to miss that. He also plans to work in the field of substance recovery, which he describes as close to his heart.

He leaves a legacy of tirelessly fighting for tenants in ways large and small and helping to tear down some of Boston’s most stubborn and entrenched barriers. The housing developments in Charlestown and South Boston are probably the most integrated neighborhoods in Boston now. Peacefully so.

It was always the small moments, he said, that showed him change was possible, recalling a scene from the early, tumultuous days of integration at Old Colony in Southie.

It was a hot summer day, and the children in the development — black and white, maybe 5 or 6 years old — were playing together in a kiddie pool in the courtyard.

“It was clear to me that those kids were going to grow up together,” McGonagle said. “And at the end of the day, they would be neighbors, and friends.”