Laurel is a city in northern Prince George's County, Maryland, United States, located midway between Washington, D.C. and Baltimore. Incorporated in 1870, the city maintains a historic district including its Main Street. The official 2007 population estimate for Laurel city was 21,619; adding the residents in Laurel's postal zip codes outside city limits, the population was 87,810 as of the 2000 census. Laurel is near Johns Hopkins University's Applied Physics Laboratory, the Fort Meade Army base, and the National Security Agency (NSA). It is also adjacent to Laurel Park Racecourse, a horse racetrack in Anne Arundel County.