Primary route
I-66
Middletown to Washington
Length76.3 mi
Designated1959
States2
Junctions3
About I-66
From Middletown, VA (I-81) to Washington, DC (US 29)
Interstate 66 is an east-west route running about 76 miles from Middletown in northern Virginia east to Washington, District of Columbia. It begins at a junction with I-81 in the Shenandoah Valley region and runs east across northern Virginia through Front Royal, Gainesville, and the inner suburbs of the Washington area before reaching the Potomac River near the District. The route is a relatively short corridor focused on the approach to the national capital.
The eastern portion through Arlington and Fairfax counties is one of the most heavily traveled commuter corridors in the Washington region, with managed lanes and time-based restrictions on parts of the route. West of the suburbs the road runs through more open country toward the Shenandoah Valley. The corridor combines long-distance access from the valley with intense suburban commuter use closer to the city.
State-by-state mileage
| State | Miles |
|---|---|
| Virginia | 74.8 |
| District of Columbia | 1.5 |
| Total | 76.3 |
History
Interstate 66 was designated in 1959 and built across northern Virginia over the following decades, with the inner suburban segments near Washington completed later amid considerable local debate. The route ends at the Potomac River approach to the District of Columbia.
Major cities and places
MiddletownFront RoyalGainesvilleArlingtonWashington
Notable features
- Potomac River approach to Washington
Did you know
- Designated in 1959 and located mostly within northern Virginia.
- One of the shorter two-digit Interstates at about 76 miles.
- Carries heavy commuter traffic with managed lanes near Washington.
- Ends at the Potomac River approach to the District of Columbia.