By 1929, Clarksburg had reached its peak population of 35,115. During the Depression the city lost industry and population, but during World War II the railroad again made it a central clearinghouse. New development came with the construction in the 1970s of Interstate 79 and the new four-lane U.S. 50 Appalachian Corridor D connecting I-79 to I-77, but plant closings in the 1980s had a negative impact. New expansion in the government and technology sectors began in the 1990s, including the relocation of the FBI Criminal Justice Information Services Center to Clarksburg and construction of a new federal building and a new building to house Fairmont State University's Clarksburg branch.