[The latest: The City Council approved the plan to close Rikers Island. Now, the hard part begins.]

Even as New York City has recorded a sharp plunge in crime in recent years, its jail complex on Rikers Island has been plagued by levels of abuse, neglect and mismanagement that have turned it into one of the country’s most notorious correctional facilities.

The dismal conditions have set off waves of protests, lawsuits and federal investigations.

Now the city will officially acknowledge the failures of its main jail by declaring that Rikers Island will be shut down, a momentous decision that supporters say pushes the city to the forefront of a national movement to reverse decades of mass incarceration that have sent African-Americans and Latinos to prison in significantly disproportionate rates.

The City Council on Thursday is expected to approve a sweeping overhaul of the nation’s second largest jail network, pledging within seven years to rebuild the corrections system with safer, smaller and more humane jails that officials say could become a model for the rest of the United States.

But the plan still faces major obstacles, including opposition to new jails in some neighborhoods where residents worry that they would harm the quality of life and criticism that the city is boxing itself in if crime were to spike or more jail cells were suddenly needed.