WASHINGTON - Nationwide housing affordability achieved near historic highs in early 2013, according to the National Association of Home Builders and Wells Fargo Housing Opportunity Index.

Overall, 73.7 percent of homes sold between January and March were affordable to families earning the U.S. median income of $64,400, slightly down from the 74.9 percent at the end of 2012.

"Thanks to very favorable mortgage rates and prices, housing affordability has remained quite high over the past four years," said NAHB Chairman Rick Judson, "The HOI has not slipped below 70 since the end of 2008. That said, from a builder's perspective, it should be noted that rising costs for building materials, lots and labor are making it somewhat more expensive to construct new homes in today's market."

At the top of the major market affordability list for the third consecutive year is Ogden-Clearfield, UT, where 93.4 percent of houses sold to the area's median earning families. On the bottom of that list is the San Francisco-San Mateo-Redwood City, CA area with 28.9 percent.