LARGE SWATHS OF mostly minority Boston neighborhoods are so heavily affected by the criminal justice system that nearly every street has a resident who has spent time in jail, a concentration of incarceration that is costing millions of dollars and threatening the social fabric of neighborhoods already struggling with high rates of poverty and other challenges.

That’s the conclusion of a study released Thursday that maps the impact on Boston neighborhood of incarceration in the Suffolk County House of Correction and Nashua Street Jail. The report, produced by The Boston Foundation, the Massachusetts Criminal Justice Reform Coalition, and the Boston think tank MassINC, says some high-poverty Boston neighborhoods have reached a “tipping point” where more imprisonment is not enhancing public safety but instead is straining the social ties that “differentiate safe neighborhoods from those afflicted by crime.”

Home addresses of those committed to the Suffolk County House of Correction (red dots) and Nashua Street Jail detainees (blue dots) in 2013.
Home addresses of Boston residents committed to the Suffolk County House of Correction (red dots) and Nashua Street Jail detainees (blue dots) in 2013.

The authors say criminal justice reform efforts now underway in the state should move aggressively to reduce incarceration rates by repealing mandatory minimum sentences, using more diversion programs to rehabilitate offenders in community settings, and bolstering education services and other programs inside jail that might help reduce recidivism rates.

Between 2009 and 2015 in the Franklin Field neighborhood of Dorchester, more than 1 in 5 men aged 25 to 29 served time in the Suffolk County House of Correction, the report found. In the Grove Hall neighborhood, about 1 of every 6 men in that age group was committed to the House of Correction during that period.

“At some point, sending more folks off to prison actually is not the answer,” said the report’s coauthor Ben Forman, research director at MassINC, which publishes CommonWealth.

Addresses in the Franklin Field neighborhood of Dorchester of those serving time in the Suffolk County House of Correction (red dots) and Nashua Street Jail (blue dots) in 2013.
Addresses in the Franklin Field neighborhood of Dorchester of those serving time in the Suffolk County House of Correction (red dots) and Nashua Street Jail (blue dots) in 2013.

The report points to several factors that research studies show contribute to that “tipping point” effect, including the normalizing of incarceration in neighborhoods to the point where it carries no stigma, the easy replacement of gang-involved offenders with new recruits, and destabilization of families and relationships when residents, many of whom are fathers, cycle in and out of correctional facilities.

“There are a lot of young men who view that as a badge of honor,” Suffolk County Sheriff Steve Tompkins said of doing time in jail.

The report found that the concentration of incarceration for more than a dozen neighborhoods, most of them heavily minority sections of Roxbury, Dorchester, and Mattapan, was greater than the neighborhood’s share of Boston residents.

State Rep. Evandro Carvalho: "When I look at the impact of some of these laws, it could have been me, so I take it personally."
State Rep. Evandro Carvalho: “When I look at the impact of some of these laws, it could have been me, so I take it personally.”

“Enough is enough,” said Tompkins during a panel discussion Thursday morning at The Boston Foundation discussing the implications of the report. “We can’t any longer afford to incarcerate as many people as we do.”

The report said the cost in 2013 of jailing Boston residents who served sentences in the Suffolk County House Correction or were held before trial in the Nashua Street Jail was more than $66 million. That represents two-and-a-half times the state funding that year for Bunker Hill Community College and Roxbury Community College, the report says.

State Rep. Evandro Carvalho, a former assistant district attorney, said the least favorite assignment of his two-and-a-half years in the Suffolk County District Attorney’s office was time he spent prosecuting cases in the county’s gun court, where he said defendants convicted of illegal gun possession were quickly cycled through and faced the state’s 18-month mandatory minimum sentence, with no discretion for judges to consider circumstances that might warrant a different disposition. (CommonWealth told the story of exactly this type of case in the magazine’s fall issue.)

Carvalho, who arrived in Dorchester from Cape Verde at age 15 and went on to earn a law degree from Howard University, said he could easily have gone astray in his neighborhood and ended up in the shoes of one of the young men he prosecuted.

“When I look at the impact of some of these laws, it could have been me, so I take it personally,” he said of the imperative he feels to push for changes.

Addresses in the Grove Hall neighborhood of Boston of those serving time in the Suffolk County House of Correction (red dots) and Nashua Street Jail (blue dots) in 2013.
Addresses in the Grove Hall neighborhood of Boston of those serving time in the Suffolk County House of Correction (red dots) and Nashua Street Jail (blue dots) in 2013.

The report comes as the state enters the final weeks of work on a review of criminal justice policies that is expected to result in legislation being introduced early next year. Last year, Massachusetts leaders began working with researchers from the Council of State Governments to study ways to improve public safety through reforms aimed at both reducing recidivism rates and corrections costs.

Massachusetts is the 25th state to sign on to the bipartisan initiative, which is trying to chart a new direction following the tough-on-crime policies of the 1980s and 1990s that have dramatically increased incarceration rates. Massachusetts has much lower overall incarceration rates than most states, but has even higher racial disparities in incarceration rates for whites and those for blacks and Hispanics.

During the panel discussion, Tompkins and John Larivee, president of Community Resources for Justice, both sounded pessimistic notes about the prospects of a sweeping reform bill emerging from the current review.

“There are a bunch of legislators that just don’t get it,” Tompkins said. “Put it in the bottom of the bird cage,” he said of reports that have offered recommendations for criminal justice policy reforms but don’t get traction on Beacon Hill.

“I don’t think there is a real sense of urgency to make big changes,” said Larivee.

Supreme Judicial Court Chief Justice Ralph Gants, who was instrumental in getting the criminal justice policy review launched, has previously called for an end to mandatory minimum drug sentences. He indicated last month, however, that legislation from the Council of State Governments initiative is likely to focus less on sentencing reform and more on re-entry programs and what he called the “back end” of the system when offenders are released from prison.

Paul Grogan, the president of The Boston Foundation, told those at the forum not to give up when it comes to pushing for comprehensive reform on Beacon Hill. “I know there’s some skepticism about what we’ll actually be able to do,” he said. “I urge you to stay with this.”