Dive Brief:

• Cities that accept federal housing funds will have to show the government how they plan to use the money to desegregate their neighborhoods, according to rules announced on Wednesday by U.S. Housing and Urban Development Secretary Julian Castro.

• Castro said the Obama administration aims to fulfill a 1968 mandate by the Fair Housing Act that the federal government not only ban racial discrimination in housing but also dismantle segregation and promote integration.

• To comply with the new rules, communities will have access to massive amounts of data that reveal the racial makeup, poverty rate, quality of schools, public transit, public housing situation and use of housing vouchers in neighborhoods. Local officials can use the data to pinpoint racially segregated communities with high poverty rates as well as neighborhoods that have no affordable housing.

Dive Insight:

Although the rules do not specify a timetable for the changes, multifamily builders, especially in the Northeast, could feel the impact in the short term as cities begin to require them to include more affordable units in condominium and apartment buildings located in mostly white, middle-class neighborhoods — in exchange for tax breaks and other incentives.

New York City already is encouraging developers to set aside some units for moderate-income tenants in high-rent neighborhoods — by allowing taller buildings. But the plan is unlikely to spur building in poor communities, the plan's critics have said.

The reason: Enough of a building's tenants must pay high monthly rents to subsidize those who can't afford to. A New York University study concluded it wouldn't be worth it for developers where rents aren't high enough to justify construction costs.

If that holds true as Obama's plan takes shape, some cities might stop taking federal housing funds.