Underground natural gas storage capacity in the Lower 48 states has remained relatively flat since 2012. The U.S. Energy Information Administration (EIA) measures working natural gas storage capacity in two ways: design capacity and demonstrated peak capacity. Both measures of capacity were relatively unchanged in 2019; design capacity declined 0.4% and demonstrated peak capacity increased 0.1% compared with 2018. For the sixth year in a row, no new storage fields were completed.