In order to more fully integrate renewable resources, such as wind and solar, into the transmission system, additional capacity must be realized in the short term using the installed transmission capacity that exists today. The U.S. Department of Energy (DOE) and the National Renewable Energy Laboratory Transmission and Grid Integration Group supported this study to assemble the history ofregulations and status of transmission technology to expand existing grid capacity. This report compiles data on various transmission technology methods and upgrades for increased capacity utilization of the existing transmission system and transmission corridors. The report discusses the technical merit of each method and explains how the method could be applied within the current regulatorystructure to increase existing transmission conductor and/or corridor capacity. The history and current state of alternatives to new construction is presented for regulators, legislators, and other policy makers wrestling with issues surrounding integration of variable generation. Current regulations are assessed for opportunities to change them to promote grid expansion. To supportconsideration of these alternatives for expanding grid capacity, the report lists relevant rules, standards, and policy changes.