Occoquan is a town in Prince William County, Virginia. The population was 934 at the 2010 United States Census. The current mayor is Earnest W. Porta Jr.

State Route 123 or Virginia State Route 123 is a primary state highway in the U.S. state of Virginia. The state highway runs 29.27 miles (47.11 km) from U.S. Route 1 in Woodbridge north to the Chain Bridge across the Potomac River into Washington from Arlington. It goes by five local names. From its southern terminus to the Occoquan River Bridge, it is known as Gordon Boulevard. From the Occoquan River Bridge to the city of Fairfax it is known as Ox Road. From Fairfax until it enters the Town of Vienna, it is known as Chain Bridge Road. Then, as it passes through the Town of Vienna, it is known as Maple Avenue. After leaving the Town of Vienna, the name reverts to Chain Bridge Road, and continues this way until the intersection with I-495 in Tysons. Between Tysons and the George Washington Memorial Parkway, it is known as Dolley Madison Boulevard. After crossing over the George Washington Memorial Parkway, the name once again reverts to Chain Bridge Road and continues this way until the end of the road, at Chain Bridge. SR 123 is a partial circumferential highway in Northern Virginia that connects Woodbridge in eastern Prince William County with the independent city of Fairfax and the Fairfax County communities of Vienna, Tysons, and McLean, the last being the home of the National Counterterrorism Center and the Central Intelligence Agency. The state highway also connects all of the major highways that radiate from Washington, including Interstate 95 (I-95), I-66, US 29, US 50, SR 267, and the George Washington Memorial Parkway. Furthermore, SR 123 crosses another pair of circumferential highways, I-495 and the Fairfax County Parkway, and SR 7, a major northwest–southeast highway through Northern Virginia. The state highway is a part of the National Highway System for its entire length.