San Francisco is one of the least affordable counties analyzed in a recent report from RealtyTrac. - 

A new report shows homes in a third of the country are getting harder to purchase for many Americans. Thursday’s RealtyTrac report looks county by county at income and housing prices to find out how affordable homes are. While they’re still affordable in much of the U.S., many people in certain areas are increasingly finding it hard to own.

“Prices are getting out of touch with what folks can actually afford in those markets,” explains RealtyTrac vice president Daren Blomquist.

In these areas, home prices are rising faster than income. This affordability problem is not so much because of a hot housing market, but rather a frosty job market. Many of those new jobs we hear about in monthly labor reports just don’t pay well enough.

“It’s particularly key in terms of first-time homebuyers that even though the rate of employment growth has gone up, the rate of wage growth hasn’t really gone up much,” says housing economist Michael Carliner.

Mortgage rates aren't likely to get much lower, so something’s got to give. Either the job market improves or home prices will hit the brakes.

Follow Mark Garrison at @GarrisonMark