In 2019, California’s net electricity imports were the largest of any state in the country at 70.8 million MWh, or 25% of the state’s total electricity supply, according to the U.S. Energy Information Administration.
Electricity routinely flows between the Lower 48 U.S. states and, to a lesser extent, between the U.S. and Canada and Mexico. Electricity generation exceeds electricity consumption in 25 states, and excess electricity is transmitted across state lines. Almost 10% of U.S. electricity generation is traded among states.
California utilities partly own and import power from several power plants in Arizona and Utah. In addition, California’s electricity imports include hydroelectric power from the Pacific Northwest, largely across high-voltage transmission lines running from Oregon to the Los Angeles area.
Although Ohio is in the top 10 states for electricity generation, it was the second-largest electricity importer in 2019. Ohio’s large population, heavily industrial economy, and wide seasonal temperature variation create high electricity demand, which at times exceeds in-state generation.
In contrast, Pennsylvania’s electricity exports were the largest of any state in 2019, at 70.5 million MWh, or 24% of total supply. Pennsylvania’s electricity generation was the third largest in the nation, behind those of Texas and Florida. Natural gas-fired and nuclear power plants produced the majority of Pennsylvania’s in-state electricity in 2019, at 43% and 36%, respectively.
EIA’s State Electricity Profiles provide data on interstate electricity trade and international imports and exports. EIA calculates net interstate electricity trade by subtracting total reported retail electricity sales, direct use, international exports, and estimated line losses from the total electricity supply.
In 2019, electricity exports from Vermont accounted for the largest share of its total electricity supply. Nearly all (99%) of Vermont’s in-state electricity generation in 2019 came from renewable sources, largely from hydropower. Additionally, electricity flows from Canada into Vermont and continues to other states, such as Massachusetts. States that imported the majority of their total electricity supply tended to be smaller, more population-dense states such as Massachusetts. Conversely, states that exported the majority of their total electricity supply tended to be geographically large, low-population-density states such as Wyoming.