The Arlington County Board has approved two major housing developments along Columbia Pike: a large apartment building for low- and moderate-income residents, and a mostly market-rate townhouse project that will replace a complex built by the federal government 70 years ago to house displaced African American families.

Board members voted unanimously to allow construction of the 229-unit Columbia Hills apartment project near the intersection of Columbia Pike and S. Frederick Street, and to lend $19 million to the Arlington Partnership for Affordable Housing (APAH) to help subsidize the project.

The vote came after midnight Tuesday, after four hours of debate in which residents of the neighboring Carlyle House condominiums argued that the new structure would be too tall and located too close to their building. The building would have eight floors above ground and three partially below ground.

“It’s like putting a size 10 foot into a size 5 shoe,” said Diana Baron, who lives at Carlyle House.

Lower-priced apartments and homes are a priority for Arlington board members and civic advocates; since 2000, Arlington has lost more than 13,500 apartments affordable to working-class families, as rents and prices have risen and more modest residences were redeveloped as upscale.

The 29,564-square-foot Columbia Hills building will be next to the affordable Columbia Grove garden apartment complex, in an area of the county that has more affordable housing than almost anywhere else.

Both the Columbia Hills project and the proposal to sell and redevelop the historic Carver Homes property were submitted to the board for approval under a special zoning code passed 2½ years ago to encourage developers to build along Columbia Pike.

By including affordable units — every apartment in Columbia Hills, and six of 73 residences on the former Carver Homes site — the developers qualified for automatic permission to build at higher density than the regular zoning laws would allow.

The Carver Homes residents had waited for years to sell their property to a developer, and were thrilled to get the board’s approval Tuesday evening for the project that will replace it.

The 44 pink garden-style townhouses sit on high ground at the eastern end of Columbia Pike near the Air Force Memorial, about 2.6 miles from where Columbia Hills will be built.

The townhouses were constructed by the federal government in 1945 after it displaced African American families evicted from the old Freedman’s Village so the Pentagon could be built.

Residents bought the properties from the government in 1949, and then formed a cooperative. Now they and their descendants are selling the property to Craftmark Homes of McLean, which will construct 50 new townhouses containing 73 residences.

Six of the units will be affordable to people who make 60 percent or less of the area’s median income.

Craftmark Homes has agreed to pay relocation assistance to any tenants in the existing Carver Homes townhouses.