Wythe County, with an area of 479 square miles, was formed in 1789 from Montgomery and named for George Wythe, a signer of the Declaration of Independence. The New River flows through the county. Grayson County, with an area of 425 square miles, was formed in 1792 from Wythe and named for William Grayson, one of the first two United States Senators from Virginia. The headwaters of the New River are in this county.