The region ranked No. 4 for affordability among major metropolitan areas in the Washington, D.C.-based association's most recent Housing Opportunity Index. The index was released last week in cooperation with Wells Fargo, the San Francisco-based bank.

The Harrisburg-Carlisle area consists of Cumberland, Dauphin and Perry counties. The median home here sold for $140,000 in the fourth quarter of 2011, and the median annual income was $72,500, meaning 91.4 percent of homes sold were affordable for the median household, the builders association said.

Lancaster County's median home sale price was $160,000 and its median income was $68,600, for an opportunity index of 88.1 percent. The association did not release figures for Lebanon or York counties.

The most affordable major metropolitan area was Youngstown-Warren-Boardman in eastern Ohio and Western Pennsylvania, where the median household can afford 95.1 percent of homes, the association said.

Nationally, the affordability index reached an all-time high of 75.9 percent. However, credit availability continues to constrain families' ability to purchase homes, the association said.