U.S. Route 1 in the District of Columbia
|Maintained by DDOT|
|Length:||7.00 mi (11 km)|
|Existed:||1926 – present|
|South end:||US 1 / I-395 on Columbia Island|
| I-395 in East Potomac Park
US 50 in Washington
|North end:||Eastern Avenue near Mt. Rainier, MD|
Route description 
U.S. Route 1 and Interstate 395 enter the District of Columbia from Virginia on the 14th Street Bridge. Route 1 traffic exits Route 395 from the left to 14th Street, S.W. After 14th Street crosses the National Mall, Route 1 turns right onto Constitution Avenue. It then turns left onto 6th Street, N.W., and then right onto Rhode Island Avenue. Route 1 continues on Rhode Island Avenue through Northeast Washington and into Maryland.
U.S. Route 1 enters the District of Columbia from Maryland on Rhode Island Avenue. Route 1 turns left onto 6th Street, N.W., then right onto L Street, N.W., and then left onto 9th Street, N.W. It enters the Ninth Street Tunnel and joins Interstate 395, which it follows into Virginia.
When originally designated in 1926, US 1 entered Washington on Bladensburg Road. The old route then continued on Maryland Avenue and turned south on 1st Street, where it then turns left into the U.S. Capitol grounds. US 1 went around the Capitol making its way to Pennsylvania Avenue. The route continues on Pennsylvania Avenue to 14th Street where it turns south. US 1 then left Washington on 14th Street as it does today. By 1946, US 1 entered from the north using Rhode Island Avenue continuing all the way to 14th Street (via Vermont Avenue). It was shifted to its current alignment by 1967.
Major intersections 
The entire route is in the District of Columbia.
|Columbia Island||0.00||0.00||I-395 south / US 1 south – Richmond, Alexandria||Continuation into Virginia|
|Potomac River||14th Street Bridges (Arland D. WIlliams Jr. Memorial Bridge / George Mason Memorial Bridge)|
|East Potomac Park||0.50||0.80||I-395 north (Southwest Freeway) – Capitol Hill, Verizon Center, Nationals Park||Northern terminus of concurrency with I-395; US 1 leaves I-395 via Exit 1; Northbound exit and southbound entrance|
|0.50||0.80||I-395 south (Rochambeau Memorial Bridge)||To HOV 3+ only; Southbound exit and northbound entrance|
|Washington Channel||14th Street Bridges (US 1 span)|
|Washington||Maine Avenue SW||Interchange; Northbound exit and southbound entrance|
|1.20||1.93||Independence Avenue SW||No left turns except from US 1 south to Independence Avenue east|
|1.50||2.41||US 50 west (Constitution Avenue NW) / 14th Street NW north||Southern terminus of concurrency with US 50|
|12th Street Expressway / 12th Street NW north||Northern terminus of 12th Street Expressway (one-way northbound)|
|9th Street Expressway south to I-395 / 9th Street NW north||Northern terminus of 9th Street Expressway (one-way southbound)
Southern terminus of one-way pairs (6th Street NW north / 9th Street NW south)
|2.10||3.38||Constitution Avenue SW east|
US 1 Alt. north (Pennsylvania Avenue NW)
|Southern terminus of US 1 Alternate; Access from US 1 north only|
|2.80||4.51||Massachusetts Avenue NW||To Union Station|
|3.00||4.83||US 50 east (New York Avenue NW)||Northern terminus of concurrency with US 50|
|US 1 west / US 50 west (L Street NW)||Northern terminus of one-way pairs|
|3.60||5.79||US 29 (Rhode Island Avenue NW west / 6th Street NW north)|
|3.80||6.12||Florida Avenue NW|
|7.00||11.27||US 1 north (Rhode Island Avenue) / Eastern Avenue NE – Baltimore||Continuation into Maryland|
Related routes 
Road concurrency 
Northbound U.S. Route 1 is concurrent with eastbound U.S. Route 50 along Constitution Avenue from 14th Street to 6th Street, N.W., and along 6th Street from Constitution Avenue to New York Avenue, N.W. Southbound U.S. Route 1 is concurrent with westbound U.S. Route 50 along L Street between 6th and 9th streets, N.W., and along 9th Street from L Street to Constitution Avenue. Both northbound and southbound Route 1 have concurrencies with Interstate 395.
|U.S. Route 1|
|District of Columbia||Next state: