Loudoun County was formed from Fairfax County in 1757.

In seventeenth- and eighteenth-century Virginia, the term "tithable" referred to a person who paid (or for whom someone else paid) one of the taxes imposed by the General Assembly for the support of civil government in the colony. In colonial Virginia, a poll tax or capitation tax was assessed on free white males, African American slaves, and Native American servants (both male and female), all age sixteen or older. Owners and masters paid the taxes levied on their slaves and servants. For a more detailed history of tithables, consult "Colonial tithables" found on the Library of Virginia's web site.