http://blogs.nicholas.duke.edu/thegreengrok/bignow/

You could just go by other research, but you could also look up the lights, fridge, and other electric devices at that time and calculate the average usage.

In the 1950s the average American consumed roughly 2,200 kilowatt-hours of electricity per year; today that number has grown to roughly 13,800 kilowatt-hours per year. (Estimates derived from population numbers here and electricity totals here [pdf].)

It looks like the DOE has records going back to 1949.
http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf