The county was named for Cecil Calvert, 2nd Baron Baltimore (1605–1675), the first Proprietary Governor of the Province (colony) of Maryland.
It is the only Maryland county that is part of the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD Metropolitan Statistical Area The area now known as Cecil County was an important trading center long before the county's official organization in 1674 by proclamation of Lord Baltimore.
No Civil War battles occurred in Cecil County, but residents had strongly divided loyalties.
It exported not only its own agricultural products but also animal skins from the west and tobacco from the south. Francis Xavier Church (Warwick, Maryland) begun as a Jesuit mission in 1704 and rebuilt in 1792, is one of Maryland's oldest churches, though now a museum. Mary Anne's Episcopal Church, authorized in 1706 and rebuilt in 1742 is another (and still in use, as well as maintaining a historic graveyard).The Principio Furnace, founded in 1719, became an important exporter of pig iron.During the American Revolution both British and colonial troops traveled through Cecil County, although no major battles occurred within its borders.Steamboats, using technology such as by Robert Fulton, came to dominate travel on the bay during the following decades.The Eagle, built in Philadelphia in 1813, transported travelers between Baltimore and Elkton, where they connected with stagecoaches to travel to Wilmington, Philadelphia and other points north.West Nottingham Academy founded by Presbyterian Rev.Samuel Finley in 1744, educated Benjamin Rush and Richard Stockton, both of whom signed the Declaration of Independence, and still operates today (though disaffiliated from the Presbyterian church and with additional buildings).British troops also destroyed most of Havre de Grace in nearby Harford County, Maryland.Cockburn's ships then traveled up the Sassafras River, and, meeting resistance, destroyed Georgetown, Maryland and Fredericktown, Maryland.Not only did British Admiral George Cockburn blockade the upper Chesapeake bay, in response to musket fire from colonials at Welch Point, his troops destroyed a trading post known as Frenchtown.They tried to sail further up the Elk River to the county seat at Elkton, but turned back under fire from Fort Defiance, also hindered by a cable across the navigation channel.