Arlington County, Va.
Salary to comfortably afford a three-bedroom: $158,474
This 208,000-population community across the Potomac River from Washington, D.C., attracts lots of wealthy suburbanites by offering a short commute to and from downtown via the Metro.
Arlington also hosts the Pentagon, which means lots of uniformed military personnel and defense contractors call the county home.
Must Read: 17M Americans Plan to Buy a Home This Year
All of that demand helped push the median Arlington three-bedroom home's price up 10% during 2013 to $693,333.
Blomquist says the only silver lining to the cloud of high home prices is that the typical Arlington household earns $100,474 a year. Still, that's less than two-thirds of what RealtyTrac estimates a family needs to comfortably afford a three-bedroom place there.
San Mateo County, Calif.
Salary to comfortably afford a three-bedroom: $170,284
High-flying Facebook has its worldwide headquarters in San Mateo County, so you might as well "unfriend" the idea of finding affordable housing there.
That's because the 718,500-population county, between San Francisco city limits and the heart of Silicon Valley, has some of America's costliest homes.
San Mateo County saw median prices for three-bedroom homes rise 13% last year to hit $745,000.
That's not surprising given that local employers include not just Facebook, but also Genentech, Oracle and other new-economy giants. The county also hosts Sand Hill Road, which is basically the Wall Street of the U.S. venture-capital industry.
But even with gigabytes of high-tech money sloshing around, the median San Mateo County family earns just $81,609 a year. That's less than half of what RealtyTrac estimates a household needs to comfortably afford a typical three-bedroom home there.
Marin County, Calif.
Salary to comfortably afford a three-bedroom: $177,922
Marin County is such a poster child for the hip-but-affluent California lifestyle that President George W. Bush once referred to "American Taliban" member John Walker Lindh (who grew up there) as "some misguided Marin County hot-tubber."
Located just north of the San Francisco line, 252,000-person Marin hosts Belvedere, Tiburon and other super-exclusive communities. Median prices for three-bedroom homes in the county rose 15% last year to reach $778,417.
Unfortunately, locals need nearly twice Marin's County's $90,535 median household income to easily afford such places. "You have to be very wealthy to buy a house in Marin County," Blomquist says.
San Francisco, Calif.
Salary to comfortably afford a three-bedroom: $228,569
If you left your heart in San Francisco, it's probably because the local home prices gave you a heart attack.
The City by the Bay has perhaps America's most-expensive housing, with median prices on three-bedroom homes rising 9% last year to a cool $1 million. Comfortably affording such a place requires more than three times the 805,000-population community's $73,012 median annual household income.
Blomquist attributes Frisco's high prices to the booming local economy, which creates strong housing demand in a city with little buildable land because it's surrounded by water on three sides.
"San Francisco is just the epitome of a market with a very-limited housing supply and it's going to be that way forever because there's a limited amount of land," he says.