Electricity routinely flows between the Lower 48 states and, to a lesser extent, between the United States 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. In 2019, California’s net electricity imports were the largest in the country at 70.8 million megawatthours (MWh), or 25% of the state’s total electricity supply. Pennsylvania’s electricity exports were the largest of any state in 2019, at 70.5 million MWh, or 24% of total supply.