State Route 28 (SR 28) is a primary state highway in the U.S. state of Virginia that traverses the counties of Loudoun, Fairfax, Prince William, and Fauquier. The route is a major artery in the Northern Virginia region, serving as an important two-lane highway in rural Fauquier and Prince William Counties, the main thoroughfare through Manassas and Manassas Park, and a high-capacity freeway through Fairfax and Loudoun counties.