The US Energy Information Administration (EIA) has data on rates for electricity usage. I got the data from this page : Average Retail Price of Electricity to Ultimate Customers by End-Use Sector, by State
I'm using just the residential prices and the data was from early in 2011.
Here are the average costs of electricity in cents per kiloWatt hour (kWh) for each state:
|District of Columbia||13.24|
The median is 10.98¢. The maximum is in Hawaii at 32.89¢. The least expensive is Idaho at 7.84¢. About 2/3 of the states are between 8.5¢ and 13.5¢.
Here's a map showing the rates split up with under 10¢ in green, 10-15¢ in yellow and over 15¢ in red:
Keep in mind that these are just averages at the state level. Simply looking up your state on the table here won't give you an accurate number for the amount you'd pay yourself. The cost varies from utility to utility within each state as well. My father's utility charges 2¢ less than the average for his state and the largest utility in his state charges 2¢ more than the state average. Individual utilities may also charge different kwh rates based on different times of the year or day.