Baltimore county was an original county in Maryland, chartered out of the widlerness at that time. There is no existent charter for the county or other act, however, other data indicates that the county was formed about 1659. Over the years the size of the county has been decreased with the last major change coming from annexation of a large area by Baltimore City in 1918 to its present limits. To aid researchers, the following maps have been prepared from the base of an 1906 Atlas map to show the changing boundaries of the county over time. In the 17th century, the boundary between Maryland and Pennsyvania was disputed and not settled until the Mason-Dixon line was surveyed in 1763-1767. Baltimore county claimed boundaries encompassed parts of Delaware and Pennsylvania in the 17th century. The western boundary of Baltimore county was not well defined until Frederick county was formed in 1748, parts of Frederick County at that time were considered Baltimore county, with most of Frederick county coming from Prince George's county (which encompassed most of Western Maryland.
Estimated boundary of the Original Baltimore county 1659-1662
Approximate Boundary of Baltimore county from 1659 to 1674, after Kent county boundary adjustment
Approximate Boundary of Baltimore county from 1674 to 1722, after Cecil county was formed from Baltimore county
Approximate Boundary of Baltimore county from 1722 to 1776, after a boundary adjustment which changed the boundary between Anne Arundel and Baltimore county from the ridge line that divided the drainage into the Patapsco and Magothy Rivers to the Patapsco river. (and also the formation of Frederick county in 1742 established the western boundary of the county).
Boundary of Baltimore county from 1776 to 1837, after Harford county was formed from Baltimore county
Boundary of Baltimore county from 1837 to 1851, after Carroll county was formed from Baltimore county and Frederick county
Boundary of Baltimore county from 1851 to 1918, after Baltimore city became a separate legal enity from Baltimore county
The current boundaries of Baltimore county have existed since 1918.
Return to the USGenWeb Baltimore county Home Page