King of Prussia is a census-designated place in Upper Merion Township, Montgomery County, Pennsylvania, United States. As of the 2010 census, its population was 19,936. The community took its name in the 18th century from a local tavern named the King of Prussia Inn, which was named after King Frederick the Great of Prussia. Like the rest of Montgomery County, King of Prussia continues to experience rapid development. One of the largest shopping malls in the United States, King of Prussia, is located here. Also located here is the headquarters of the Nuclear Regulatory Commission Region I. King of Prussia is considered to be an edge city of Philadelphia, consisting of large amounts of retail and office space situated at the convergence of four highways.