Salt Lake City Air Route Traffic Control Center (ZLC) (radio communications "Salt Lake Center") is one of 22 FAA Area Control Centers in the United States. It is located in Salt Lake City, Utah, adjacent to Salt Lake City International Airport. It was opened in 1939 and was originally located on the third floor of the old Salt Lake City International Airport terminal. The Salt Lake Center (ZLC) covers one of the largest geographical areas of any other control center, totaling approximately 350,000 squares miles.