Because average prices for similar goods are much higher in California or New York than in Mississippi or South Dakota, The Tax Foundation notes points out that the same amount of dollars will buy you comparatively less in the high-price states, or comparatively more in low-price states. Regional price differences are strikingly large, and have serious policy implications. The same amount of dollars are worth almost 40 percent more in Mississippi than in DC, and the differences become even larger if metro area prices are considered instead of statewide averages.
For example, Tennessee is a low-price state, where $100 will buy what would cost $110.25 in another state that is closer to the national average. You can think of this as meaning that Tennesseans are about ten percent richer than their nominal incomes suggest.
The states where $100 is worth the least are the District of Columbia ($84.60), Hawaii ($85.32), New York ($86.66), New Jersey ($87.64), and California ($88.57). That same money goes the furthest in Mississippi ($115.74), Arkansas ($114.16), Missouri ($113.51), Alabama (113.51), and South Dakota ($113.38).
A person who makes $40,000 a year after tax in Kentucky would need to have after-tax earnings of $53,000 in Washington, DC just in order to have an equal standard of living, let alone feel richer.