When a woman in McKinney, Texas, told Tatiana Rhodes and her friends to “go back to your Section 8 homes” at a public pool earlier this month, she inadvertently spoke volumes about the failure of a program that was designed to help America’s poor.

Created by Congress in 1974, the “Section 8” Housing Choice Voucher Program was supposed to help families move out of broken urban neighborhoods to places where they could live without the constant threat of violence and their kids could attend good schools....

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....

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.