Interstate 395 (I-395) in Washington, D.C., and Virginia is a 13-mile-long (21 km) spur route that begins at a junction with I-95 in Springfield and ends in northwest Washington, D.C. It passes underneath the National Mall near the U.S. Capitol and ends at a junction with U.S. Route 50 (US 50) at New York Avenue, roughly a mile (1.6 km) north of the 3rd Street Tunnel. Despite its proximity to Interstate 395 in Maryland, the route is unrelated and unconnected.

The intersection where I-395, I-95, and the Capital Beltway meet is called the Springfield Interchange.

Unofficially, this interchange is also referred to as The Mixing Bowl. This moniker causes confusion, because the intersection of I-395, Washington Boulevard, and Columbia Pike several miles north was historically known by that name, and continues to be recognized by the Virginia Department of Transportation as such.

I-395 contains a reversible, barrier-separated HOV facility, also known locally as the "express lanes", with its own entrances and exits, provided as a third roadway of Interstates 395 and 95 between South Eads Street near the Pentagon in Arlington County and State Route 234 in Prince William County, Virginia. During rush hour, the HOV facility operates in the direction of rush-hour traffic and is restricted to vehicles containing three or more passengers. Motorcycles, alternative fuel cars, hybrids registered in Virginia before July 1, 2006, and federal law enforcement vehicles are also permitted to use HOV lanes, even if carrying only one occupant. At other times, the facility is either open to all traffic in one direction or closed to all traffic. In 2012, the exemption was modified to be "open-ended" rather than year-to-year.

The facility was initially constructed with a single lane as the first busway in the United States before being expanded and converted to HOV use. Approximately 65% of travelers on I-395 (61,000 commuters) utilized the HOV lanes during the morning rush hour: 32,000 rode transit and 29,000 used private vehicles with 2 or more people. 33,000 commuters (35% of total users) drove alone.

I-395 and US 1 cross the Potomac River from Virginia to Washington, D.C., on three parallel four-lane bridges, together known as the 14th Street Bridge. Potomac River crossings for the Washington Metro's Yellow Line and for a major CSX railroad line are immediately downstream here. This site has long been a major Potomac River crossing, with the first bridge constructed here in 1809. Of the present highway spans, the eastern one was built in 1950, the western one in 1962, and the central one in 1972.

During an evening rush-hour snowstorm in 1982, Air Florida Flight 90 crashed on take-off from National Airport, hitting the easternmost of the three highway bridges. The oldest span, formerly named the Rochambeau, is now named the Arland D. Williams, Jr. Memorial Bridge, in honor of a passenger of Flight 90 who survived the crash, escaped from the sinking aircraft, and perished in the Potomac River while saving others from the icy waters. The center span is now called the Rochambeau Bridge, and the western span, the George Mason Memorial Bridge.

The following names are used for I-395 in the District: the Southwest Freeway from the 14th Street Bridge to the Southeast Freeway interchange (I-695), the Center Leg or Center Leg Freeway from the Southeast Freeway interchange to New York Avenue, and the Third Street Tunnel for the segment of the Center Leg under the National Mall.

The portion of Interstate 395 between the Pentagon in Arlington, Virginia, and the interchange with Interstate 95 and the Capital Beltway in Springfield is part of the Henry G. Shirley Memorial Highway, named for a Virginia Highway Commissioner who died on July 16, 1941, just a few weeks after approving work on the new expressway. Originally State Route 350, the full length of the Shirley Highway was opened on September 6, 1949, from south of the Pentagon to Woodbridge, Virginia, along what is now better known as the Interstate 95 corridor. The Shirley Highway featured the nation's first reversible bus lanes, a precursor to today's HOV lanes.

Original plans called for I-95 to travel through Washington, D.C., and Prince George's County, Maryland, toward the northeastern portion of the Capital Beltway, from which I-95 presently continues its northbound route. However, neighborhood opposition in the District halted this plan in 1977, diverting planned funding toward construction of the Washington Metro. The only remnant of the Maryland extension is a series of ramp stubs near College Park, which now lead to a Park & Ride. The portion of I-95 within the Beltway became I-395, while the eastern half of the Beltway was re-designated I-95 (and, later, co-signed I-95/I-495). I-395 currently terminates in Washington, D.C., at a traffic signal at U.S. Route 50, which is New York Avenue, near Mount Vernon Square.

The District government finalized a deal in 2010 with the Louis Dreyfus Group to construct a 2,100,000-square-foot (200,000 m2) mixed-use development in the airspace over the Center Leg Freeway portion of Interstate 395. The $425 million office, residential, and retail project at the east end of the Judiciary Square neighborhood will also restore the area's original L'Enfant Plan street grid by reconnecting F and G Streets over the freeway. The project is awaiting final regulatory approval and is expected to be complete by 2016.

Exits in Virginia are numbered south to north, in accordance with AASHTO guidelines. Exits in the District of Columbia were unnumbered until 2008, when signs were posted numbering them sequentially south to north.[citation needed]