Baltimore County ( , locally: or ) is the third-most populous county in the U.S. state of Maryland and is part of the Baltimore metropolitan area. Baltimore County (which partially surrounds, though does not include, the independent City of Baltimore) is part of the Northeast megalopolis, which stretches from Northern Virginia northward to Boston. Baltimore County hosts a diversified economy, with particular emphasis on education, government, and health care. As of the 2020 census, the population was 854,535. The county is home to multiple universities, including Goucher College, Stevenson University, Towson University, and University of Maryland, Baltimore County. History The name "Baltimore" derives from Cecil Calvert, 2nd Baron Baltimore (1605–1675), the proprietor of the new colony in the Province of Maryland, and the town of Baltimore in County Cork, Ireland. The earliest known documentary record of the county is dated January 12, 1659, when a writ was issued on behalf of the General Assembly of Maryland to its sheriff. The official founding of the county came in 1659, among the now 23 counties of the State of Maryland. This assumes that a certain amount of organization and appointments in the mid-17th century had already occurred. Previously, (old) Baltimore County was known more as a geographical entity than a political one, with its territorial limits including most of northeastern Maryland, which was then the northwestern frontier of the Province and included the present-day jurisdictions of Baltimore, Cecil and Harford Counties, and parts of Carroll, Anne Arundel, Frederick, Howard, and Kent Counties. In 1674, a proclamation of the Proprietor established the then-extensive boundary lines for old Baltimore County. Over the next century, various segments of the old county were sliced off as population and settlements increased in fringe regions. A portion of northeastern Baltimore County, as well as a portion of northwestern Kent County, was split off to create Cecil County. In 1748, a portion of western Baltimore County, as well as a portion of Prince George's County to the south, were split off to create Frederick County. In 1773, Harford County to the east was split off, and in 1837 another part of western Baltimore County was combined with a part of eastern Frederick County to create Carroll County. After the adjustment of Baltimore County's southern boundary with Anne Arundel County, stated to be the upper Middle and Western Branches of the Patapsco River in 1727, a portion of the county's