Stress City, U.S.A.

"We examined the country's 40 largest U.S. Census-defined metropolitan statistical areas and looked at quality of life indicators. We tracked housing affordability based on the August 2008 National Association of Home Builders/Wells Fargo housing opportunity index and unemployment rates for the same month based on data provided by the Bureau of Labor and Statistics. We also worked cost of living into our ranking by factoring in the price for one gallon of gas on Sept. 4 per a daily survey conducted by insurance company AAA."

"But consumers aren't fretting about these pressures in a vacuum. A city's environment can play a big role in how its citizens are able to cope with stress."

"In order to capture the way a city's environmental factors can impact nerves we looked at 2007 air quality using air monitoring data that states submitted to the U.S. Environmental Protection Agency (EPA) from 2003-05. Then we pulled the number of sunny days per year using 2007 data furnished by the National Environmental Satellite, Data and Information service. Finally, we looked at population density based on 2007 data furnished by the U.S. Census Bureau to find the cities most squeezed for livable space."