Buchanan County is a county located in the U.S. state of Virginia. As of the 2010 census, the population was 24,098. Its county seat is Grundy. As of 2009, it was the poorest county in the state of Virginia and one of the 100 poorest counties in the United States, when ranked by median household income.
The county was formed in 1858 from parts of Russell County and Tazewell County. It was named for James Buchanan, the 15th President of the United States. In 1880 the southwestern part of Buchanan County was combined with parts of Russell County and Wise County to become Dickenson County.
Helen Timmons Henderson (1877–1925) helped participate in the work of the Buchanan Mission School at Council, Va. She and Sarah Lee Fain (1888–1962) of Norfolk became the first two women to be elected into the Virginia General Assembly. They were both Democrats in the House of Delegates. When Helen was in office, the delegates agreed to let 6.2 miles of improved road to be placed from Russell County, across Big "A" Mountain, to Council. Route 80 is also known as "Helen Henderson Highway, In 1876, Grundy was chosen and became the county seat of Buchanan County, it was named in honor of Felix Grundy, a Senator from Tennessee.