least expensive/most expensive american cities to live in

Hey, maybe they're the most stressful. Just kidding.

Look at www.salary.com and you'll see what people are paid. That will give you an idea of what's expensive.

For expensive, it's the obvious places: New York, LA, San Francisco and Honolulu are way up there.
For least expensive, it's also the usual suspects: places in the South and West that tend to not be considered as "trendy" (that's not a hard and fast rule, but it does seem to apply a lot).

Why are you asking anyway?

Typically, the more a city has to offer, the more it costs to live there. According ACCRA, a non-profit organization that researches community and economic development -In order of most expensive New York, New York, Jersey City, New Jersey, San Francisco, California, Stamford, Connecticut, Honolulu, Hawaii,
Least expensive: McAllen, Texas, Seguin, Texas, Laredo, Texas, Jonesboro, Arkansas, Lubbock, Texas

I just now heard on the news that the top four are in New England, as far as property taxes go.