The first Rappahannock County, Virginia, was founded in 1656 from part of Lancaster County, Virginia and became extinct in 1692 when it was divided to form Essex County and Richmond County, Virginia. The county was named for the Native Americans who inhabited the area, Rappahannock reportedly meaning "people of the alternating (i.e., tidal) stream." The county's origins lay in the first efforts by English immigrants to "seat" the land along the Rappahannock River in the 1640s. The primitive travel capabilities of the day and the county's relatively large area contributed to the settlers' hardship in travel to the county seat to transact business, and became the primary reason for the county's division by an Act of the Virginia General Assembly in 1691 to form the two smaller counties.
In 1833, a new Rappahannock County was founded in a different location, created from Culpeper County, Virginia, and named after the Rappahannock River.