Linthicum is a census-designated place (CDP) and an unincorporated community in Anne Arundel County, Maryland, United States. The population was 7,539 at the 2000 census. It is the approximate location of Baltimore-Washington International Thurgood Marshall Airport (BWI). Formally known as Linthicum Heights, the designated name of the zip code 21090, Linthicum has been traditionally divided into two distinct communities each with its own community association and identity. These two communities are North Linthicum and Linthicum-Shipley. Both communities developed as a result of their location adjacent to the Baltimore and Annapolis Railroad line, which brought commuters to the original truck farm community.
Linthicum was founded in 1908 and named for Abner Linthicum. The Linthicum Heights Historic District was listed on the National Register of Historic Places in 2006.
Linthicum is located at 39°12′14″N 76°39′38″W / 39.20389°N 76.66056°W / 39.20389; -76.66056 (39.203876, -76.660506).