Northumberland County is situated on the Northern Neck of Virginia, a peninsula bounded by the Rappahannock and Potomac Rivers and the Chesapeake Bay. Heathsville, the county seat, is 120 miles southeast of Washington, DC, 70 miles east of the state capital of Richmond, and 70 miles northeast of Williamsburg. The county's 223 square miles are mostly flat to gently rolling terrain.

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