Section 1221(a) of the Energy Policy Act of 2005, codified at 16 U.S.C. 824p(a), directs the Secretary of Energy to conduct an electric transmission congestion study every three years, and to prepare it in consultation with affected states and regional reliability organizations. In the study, the Department seeks to provide information about transmission congestion. The Department has published two previous congestion studies, one in 2006 and another in 2009.

The National Electric Transmission Congestion Study released in September 2015 seeks to provide information about transmission congestion by focusing on specific indications of transmission constraints and congestion and their consequences. The study focuses primarily on historical trends over the past few years, and looks into the future to the extent possible. It does not apply congestion labels to broad geographic areas such as the “critical congestion areas,” “congestion areas of concern,” and “conditional congestion areas” identified in earlier studies. For analytic convenience, the study’s results are presented and discussed in relation to four large regions of the United States: the West, Midwest, Northeast, and Southeast. The area covered by the Electric Reliability Council of Texas (ERCOT) is excluded by law from this study. The study, and the accompanying Report on Designation of National Corridors, are available below for downloading.