Coordinates 39°24'N 76°36'W? / ?39.4, -76.6Baltimore County is primarily suburban in character. It forms part of the Baltimore-Washington Metroplex.
The origin of Baltimore County is not known, the earliest known record of the county politically is January 12, 1659, when a writ was issued to its sheriff. Previously, Baltimore County was more known as a geographical entity than a political one, with its territorial limits consisting of the present day Baltimore City, Cecil and Harford Counties, as well as parts of Carroll, Anne Arundel, Frederick, Howard and Kent Counties.
In 1674, a portion of Baltimore County, as well as a portion of Kent County, was split off to form Cecil County. In 1748, a portion of Baltimore County, as well as a portion of Prince George's County, was split off to form Frederick County. In 1773, Harford County was split off from Baltimore County. In 1837, a part of Baltimore County was combined with a part of Frederick County to form Carroll County. As mentioned above, in 1851 the city of Baltimore was detached from Baltimore County.