With the number of homeless people in New York City reaching an all-time high, Mayor Bill de Blasio unveiled a five-year plan in February to reduce homelessness and provide better services by opening 90 new shelters and expanding 30 existing ones. As the de Blasio administration rolls out the plan, where the city decides to put the additional shelters has grown contentious.

The city’s primary shelter system is a patchwork of dormitories, family shelters, commercial hotel rooms and apartments in private buildings known as cluster apartments. Under the mayor’s plan, new and expanded shelters are to replace the hotel rooms and apartments that are scattered throughout 360 different sites across the city.

Bronx Number of people housed in shelters,

by ZIP code Man. 500 Queens 50 Brooklyn Staten Island Number of people housed in shelters, by ZIP code Bronx 500 250 50 Manhattan Queens Brooklyn Staten Island Cluster Apartments Bronx Man. Queens Brooklyn Staten Island Bronx Manhattan Queens Brooklyn Staten Island Hotels Bronx Man. Queens Brooklyn Staten Island Bronx Manhattan Queens Brooklyn Staten Island Traditional Shelters

The primary goal of the de Blasio administration is to house homeless people in the communities in which they became homeless, and it has chosen to use the boundaries of the city’s 59 community districts to determine where shelters should be placed.

Mr. de Blasio said he believed homeless people were better positioned to find permanent housing if they were placed in shelters close to neighborhood anchors, like schools, churches, jobs and relatives.

Right now, some community districts shoulder a large concentration of homeless shelters, and residents — including those who have sued the city unsuccessfully — have questioned why the de Blasio administration chose community districts. The answer is this: Some neighborhoods share ZIP codes but are in different community districts, and it is through districts, not neighborhoods, that city services are generally delivered.

Eric Adams, the Brooklyn Borough president, has argued that someone who becomes homeless in working-class Crown Heights could live in a shelter in nearby, wealthier Park Slope without feeling displaced.

Wakefield More people became homeless here than are sheltered here Pelham Parkway Bronx High Bridge More people are sheltered here than became homeless here Soundview East Harlem Upper West Side 2,000 1,000 500 Midtown Elmhurst Floral Park Manhattan Lower East Side Queens Bedford Stuyvesant South Jamaica Brownsville Sunset Park Brooklyn Flatbush West Brighton Flatlands Bensonhurst New Springville Somerville Gravesend Staten Island More people became homeless here than are sheltered here More people are sheltered here than became homeless here 2,000 Bronx 500 Man. Queens Brooklyn Staten Island Wakefield More people became homeless here than are sheltered here Manhattan High Bridge Bronx More people are sheltered here than became homeless here East Harlem Midtown 2,000 Floral Park Queens 1,000 500 Bedford Stuyvesant South Jamaica Brownsville Sunset Park West Brighton Flatbush Brooklyn Staten Island Somerville Gravesend Based on a census of shelter residents in Oct. 2016.

The mayor’s plan runs counter to efforts by the City Council to improve “fair share” laws aimed at distributing amenities and social services equitably throughout the city. And in a city that is already deeply segregated, neighborhood shelters are likely to be segregated as well.

Bronx Newly opened shelters under the mayor’s plan Man. Queens Brooklyn Staten Island

So far, only five new shelters have opened, and they set off controversy, especially in Crown Heights. The administration recently announced sites for two more shelters in the Bronx but has not said where the rest will go. Here are some of the factors they might consider.

Currently, the city’s poorest areas have more shelter space than they need to house those who became homeless nearby.

Bronx City ZIP codes where the percentage of families in poverty exceeds 30 percent Man. Queens Brooklyn Staten Island Percentage of city’s homeless population who: Became homeless here 35% Live in a shelter here 41% City ZIP codes where the percentage of families in poverty exceeds 30 percent Bronx Percentage of city’s homeless population who: Became homeless here 35% Man. 41% Live in a shelter here Queens Brooklyn Staten Island

Areas with fewer poor people, often adjacent to the poorest areas, tend to have fewer shelters than needed.

Bronx City ZIP codes where the percentage of families in poverty is 15 to 30 percent Man. Queens Brooklyn Staten Island Percentage of city’s homeless population who: 49% Became homeless here Live in a shelter here 38% City ZIP codes where the percentage of families in poverty is 15 to 30 percent Bronx Percentage of city’s homeless population who: Became homeless here 49% Man. Live in a shelter here 38% Queens Brooklyn Staten Island

Many people become homeless in areas that have no shelters.

Some areas, including parts of Staten Island, northeast Queens and Bay Ridge, Brooklyn, produce homelessness but have no shelters at all. And they could be selected as locations for new shelters under the mayor’s plan. Staten Island has more than 1,200 homeless people, but only one shelter with space for 135 residents.

Bronx Number of people who became homeless in a ZIP code without a shelter Inwood Parkchester 500 Areas with no shelters 100 5 Lincoln Square Manhattan Chelsea Queens Village Queens Glendale Newly opened shelters under the mayor’s plan St. Albans Red Hook Laurelton Brooklyn Arlington Bay Ridge Emerson Hill Bath Beach Grasmere Staten Island Coney Island Number of people who became homeless in a ZIP code without a shelter Bronx Man. 500 Queens 100 5 No shelters Brooklyn Staten Island Bronx Number of people who became homeless in a ZIP code without a shelter Inwood Parkchester Areas with no shelters 500 Manhattan 100 5 Lincoln Square Chelsea Queens Queens Village Newly opened shelters under the mayor’s plan Glendale St. Albans Red Hook Laurelton Brooklyn Arlington Bay Ridge Emerson Hill Bath Beach Grasmere Staten Island Coney Island Circles are based on the number of people in city homeless shelters who identified these ZIP codes as including their last addresses. People who become homeless in a ZIP code without a shelter can be housed in a shelter in the same community district.

Areas that currently house the homeless in hotels and cluster apartments will need more shelters.

These are areas where existing shelter beds would be overwhelmed by the administration’s plan to move everyone out of apartments and hotels.