War-related buildup at defense facilities for World War II added to area population in the 1940s. The 1960s brought renewed growth and development, fueled by the construction of Interstate 95, which eased commuting and trade. By the 1970s, the city and the area had become a bedroom community for jobs in Northern Virginia and Washington, D.C.. Headquarters agencies, lobbyists, consultants, defense and government contractors, and a range of other businesses were part of the regional economy influenced by the U.S. government. The city also benefited by its relative proximity to four military installations: the United States Marine Corps' Quantico Base, the U.S. Army's Fort Belvoir, the U.S. Navy's Dahlgren Surface Weapons Base, and the Virginia National Guard's Fort A.P. Hill.