When it comes to buying a home, America's affordability gap is growing ever wider.
For the typical American household earning the median income, 65.5% of homes were affordable during the first quarter, according to a survey by the National Association of Home Builders (NAHB) and Wells Fargo Bank's Housing Affordability Index.
Where homes are affordable (and not)
Median home price
% of homes that are affordable
Santa Ana, Calif.
San Jose, Calif.
Source: National Association of Home Builders and Wells Fargo Bank. The Housing Opportunity Index is based on median home prices, median household income and interest rates during the first quarter of 2014. The percentage of affordable homes sold during the quarter were those that could be afforded by households earning the median income.
But in cities like San Francisco, Los Angeles, New York, Boston and Denver, where prices are soaring, it's much more difficult for the average earner to afford a home.
"High-cost cities are rebounding faster than low-cost ones," said David Crowe, chief economist for the NAHB. "Unusually large increases in wealth have driven up prices."
InSan Francisco -- the most expensive metro market in the nation with a median home price of $815,000 -- only 13.3% of homes could be purchased comfortably by households earning the median income of $100,000. That was down from 28.9% in 2013.
Expensive cities tend to keep growing more expensive because they're already so densely packed with housing. "A way to keep prices down is to add to the supply by building new homes," said Crowe.
But that's harder to do in places where there's not much land to build on due to coastlines or mountains.
Meanwhile, the most affordable U.S. cities tend to be in the Midwest and Northeast, predominantly in old industrial towns where the economy is no longer expanding and there is plenty of land to build on.
In Syracuse, N.Y. , for example, nearly 94% of homescould be comfortably paid for by a family earning the median income, according to NAHB's index. That's up from 91.6% a year before.
Helping Syracuse's residents better afford homes is its high median income of$67,700, which is about $4,000 higher than the national median. That goes a long way toward affording a home in the area, where the median price of a home is just $94,000.