Anne Arundel County, also notated as AA or A.A. County, is located in the U.S. state of Maryland. As of the 2020 United States census, its population was 588,261, an increase of just under 10% since 2010. Its county seat is Annapolis, which is also the capital of the state. The county is named for Anne Arundell, Lady Baltimore, a member of the ancient family of Arundells in Cornwall, England, and the wife of Cecilius Calvert, 2nd Baron Baltimore (1605–1675), founder and first lord proprietor of the colony Province of Maryland.

The Washington–Baltimore combined metropolitan statistical area is a statistical area including the overlapping metropolitan areas of Washington, D.C. and Baltimore. The region includes Central Maryland, Northern Virginia, three counties in the Eastern Panhandle of West Virginia, and one county in south-central Pennsylvania. It is the most educated, highest-income, and third-most populous combined statistical area in the United States behind New York City–Newark, NJ and Los Angeles–Long Beach.