Business In 1943, US built an entire city, and it didn’t exist on a single map by Marcus Liu - Business Editor July 27, 2026 by Marcus Liu - Business Editor July 27, 2026 Oak Ridge, Tennessee, operated for seven years as a secret city housing 75,000 residents during World War II while producing enriched uranium for the Manhattan Project. The U.S. government acquired … 0 FacebookTwitterPinterestEmail