Average on-peak, day-ahead wholesale electricity prices rose in every region of the Lower 48 states in first-half 2013 compared to first-half 2012. The most important factor was the rise in the price of natural gas in 2013 compared to 10-year lows in April 2012. However, the increase in power prices was not uniform across markets as regional natural gas supply issues drove larger increases in the Northeast and Pacific Northwest.

via Today in Energy http://www.eia.gov/todayinenergy/detail.cfm?id=12211