There is a large difference in the cost of living between areas like SF and NYC and the average, but it is not nearly that high. The living wage for a family of two adults, and two children, with one working, for San Francisco is $72k according to http://livingwage.mit.edu/counties/06075 Chattanooga TN has the lowest of a major city at $47k in income for the same size family. Over 50% of households in the bay area make less than $75k a year. It is a hyperbole to say that $100k is poor even in the bay area