But the fair market rent cut-off point often consigns voucher-holders to impoverished neighborhoods. This is in part because of how that number is calculated: HUD draws the line at the 40th percentile of rents for “typical” units occupied by “recent movers” in an entire metropolitan area, which includes far-flung suburbs with long commutes and, as a result, makes the Fair Market Rent relatively low. In New York City, for example, the Fair Market Rent for a one-bedroom is $1,249, a price that would relegate voucher-holders to the neighborhood of Brownsville in Brooklyn, one of the most dangerous places in the city, and where the most public housing is located.

Technically, voucher holders can live anywhere in a region that meets the price restrictions. But the tendency is for people to stay in neighborhoods that are familiar to them, though a few areas have created robust mobility-counseling programs to try and mitigate this. Additionally, as Eva Rosen has detailed, landlords in low-income areas aggressively recruit voucher-holders, as the vouchers are a much more reliable source of rent than other low-income tenants have available.

The failings of Section 8 go far beyond flaws in how the program was designed to how the the states have implemented it. People can argue all they want about the merits of subsidized housing, but given that Section 8 exists, it would seem advantageous for states and municipalities to take advantage of federal funds to help families find better housing. But many states seem especially determined to keep voucher-holders in areas of concentrated poverty.

“The whole idea of Section 8 in the beginning was that it was going to allow people to get out of the ghetto,” said Mike Daniel, a lawyer for the Inclusive Communities Project, told me. (Daniel has sued HUD over the way it is carrying out the program in Dallas.) “But there’s tremendous political pressure on housing authorities and HUD to not let it become an instrument of desegregation.”

For example, in much of the country, landlords can refuse to take Section 8 vouchers, even if the voucher covers the rent. And, unlike the landlords in poor neighborhoods in Eva Rosen’s study, many landlords of buildings in nicer neighborhoods will do anything to keep voucher-holders out. The result is that Section 8 traps families in the poorest neighborhoods.

One study in Austin found that there were plenty of apartments around the city that voucher-holders could afford. But only a small portion of those apartments would rent to voucher-holders.

The report, by the Austin Tenant’s Council, found that 78,217 units in the Austin metro area—about 56 percent of those surveyed—had rents within the Fair Market Rent limits. But only 8,590 of those units accepted vouchers and did not have minimum income requirements for tenants. Most were located on the east side of Austin, in high-poverty areas with underperforming schools and high crime rates. (The survey only looked at apartment complexes with at least 50 units.)