The social and economic cost of the incarceration is high, and it has been disproportionately borne by black and Hispanic communities. Yet research strongly suggests that incarceration had little to do with the decrease in crime, and in fact may have contributed to crime. “We’ve thrown jail at every problem for so long. We know now that we were wrong,” said Scott Hechinger, senior staff attorney and director of policy at Brooklyn Defender Services. “It doesn’t enhance safety. It does the opposite, and it costs a fortune.”

Rikers continues to be a place of violence and cruelty. In 2010, a 16-year-old African-American by the name of Kalief Browder was accused of stealing a backpack, a crime he said he did not commit, and sent to Rikers . The teenager never received a trial. Yet he remained in jail for three years, including two years in solitary confinement. In 2015, two years after his release, he took his own life, after speaking openly about the trauma the ordeal had caused him.

Mr. Browder’s death galvanized the movement to close Rikers Island once and for all. For several years, Mayor Bill de Blasio resisted those calls. In 2017, the mayor — after his re-election and under enormous pressure from community groups — backed a plan to close Rikers.

Though the plan has significant support, it isn’t a sure thing. Over the past year, New Yorkers and the officials who represent them have argued over the important details of how to close the complex and what to do with the jails that would replace it.

The plan is supported by the mayor, the City Council speaker, Corey Johnson, and many criminal justice advocates . The new jails would be modern facilities closer to courthouses and communities. Many experts have said building new jails on Rikers Island is impossible, partly because it is close to the runways of La Guardia Airport, limiting the scale of development. They have also said the isolation of the island, combined with a deeply entrenched culture of corruption and violence, is reason enough to close the jails and start anew.

The plan calls for the city to spend more than $8 billion to rebuild three outdated jails, one each in Brooklyn, Queens and Manhattan, to make them safer and more sanitary , and able to accommodate education, mental health and job training services. A fourth jail would be built in the Bronx, which never had a permanent facility, to the same standards. Staten Island would be the only borough without a jail because its residents represent a tiny portion of the city’s jail population.

There has been some community opposition to the plan in places where the jails would be built or expanded. Local officials are divided over the plan in the Bronx, where some residents have said they don’t want a jail near their homes. At community meetings in the Boerum Hill neighborhood of Brooklyn, many residents have opposed plans to expand the existing jail. Councilman Stephen Levin, who represents the area, has signaled support for rebuilding the Brooklyn jail, but also wants investments in restorative justice programs, mental health, education and health care.