The county is named for Anne Arundell (c. 1615/1616–1649), 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.

[4] On March 25, 1655, after the English Civil War, (1642–1651), in Europe, the Battle of the Severn, the first naval colonial battle ever fought in North America, was fought in Anne Arundel County on the Severn River between Puritan forces supporting the Commonwealth of England and forces loyal to Lord Proprietor Cecilius Calvert.

[6] Between 1694 and 1695, the provincial capital of Maryland was moved from St. Mary's City along the northern shore of the Potomac River across from the southern colonial border with the Province of Virginia in St. Mary's County farther north along the western shore of the Chesapeake Bay, midway in the colony to Annapolis in Anne Arundel County.

[7] During the American Revolutionary War, citizens of Anne Arundel County supported the Continental Army by providing troops for three regiments.

[citation needed] On May 22, 1830, the inaugural horse-drawn train of the Baltimore and Ohio Railroad travelled the 13 miles (21 km) of the newly completed track from Mount Clare Station in southwestern Baltimore to Ellicott Mills, (now Ellicott City), then in the Western or Howard District (now Howard County) of Anne Arundel County.

[9] In 1831, land west of the railroad was considered the Howard District of Anne Arundel County.

Further south, the upper Patuxent River forms the border of Anne Arundel with Prince George's County to the west.

The Patapsco River to the north is the border with Baltimore County, but the communities and areas of Brooklyn and Curtis Bay neighborhoods (and adjacent Fairfield, Wagner's Point [also known as East Brooklyn], Arundel Cove [off of Curtis Creek], and Hawkins Point), lying south of the Patapsco River were annexed from Anne Arundel County to Baltimore in the third major annexation of January 1919.

The northwestern section of this long tract later became Howard County, with the border between the two running very close to the Atlantic Seaboard fall line.

[citation needed] Elevations in Anne Arundel County range from sea level at the Chesapeake and tidal tributaries to about 300 feet (91 m) in western areas near the fall line.

[15] The terrain is mostly flat or gently rolling, but more dramatic banks and bluffs can be found where waterways cut through areas of higher elevation.

[citation needed] With the exception of the very limited extent of Piedmont underlain by Precambrian to early Paleozoic metamorphic rock, all of the county is underlain by thick deposits of gravel, sand, silt, and clay dating from the early Cretaceous to Holocene times.

[17] Anne Arundel County has a humid subtropical climate, with hot summers and cool winters.

Annual snowfall totals around 20.1 in (51 cm) on average at BWI Airport, which has an elevation of 156 ft (47.5 m) above sea level.

[citation needed] The Democrats have the most registered voters in the county, but the large number of Republican-leaning independents means Republicans win more county-wide elections than in other mostly suburban counties in Maryland, but Democrats are the dominant party in Annapolis city elections.

[25] Several major law enforcement agencies serve Anne Arundel County: In the 119th Congress, Anne Arundel County is represented in the U.S. House of Representatives by Sarah Elfreth (D) of the 3rd district, and Steny Hoyer (D) of the 5th district.

About 2.63% of the population were Hispanic or Latino of any race; 17.7% were of German, 13.1% Irish, 10.5% English, 8.1% United States or American, and 7.0% Italian ancestry.

[citation needed] According to the Maryland Department of Business and Economic Development, the following were the principal employers in the county in November 2014 (excluding U.S. post offices and state and local governments, but including public institutions of higher education).

[citation needed] Several state agencies are headquartered in unincorporated areas in Anne Arundel County.

[47] Anne Arundel County is the home of Baltimore-Washington International Thurgood Marshall Airport, commonly referred to as BWI.

The southern portion of the Maryland Transit Administration's Light Rail system, connecting downtown Baltimore with BWI, runs through the northern part of Anne Arundel County.

The Laurel-based Connect-a-ride system operates two routes in the western portion of the county, including Severn, Arundel Mills, Maryland City, Glen Burnie, Hanover, and Odenton.

[50] Helen Avalynne Tawes Garden is located at the Department of Natural Resources headquarters in Annapolis.

[52] The Department of Recreation and Parks maintains "a comprehensive system of recreational programs for county residents and the preservation of valuable land," including indoor and outdoor sports facilities, community parks, green ways, archaeological, environmental, and historical preserves, and large regional facilities.