Science Fair Project Encyclopedia
Interstate 495 (Capital Beltway)
The Capital Beltway (Interstate 495) is a freeway-class interstate highway which circles the Washington, DC area. It is the basis for the phrase "inside the Beltway", used when referring to issues dealing with American government and politics.
The federal government gave final approval for the construction of the Capital Beltway (also known as the Circumferential Highway in the planning stages) on September 28, 1955. The first section of the 64-mile long Beltway (including the Woodrow Wilson Memorial Bridge over the Potomac River) was opened on December 21, 1961; the highway was completed on August 17, 1964.
Originally designated I-495, in 1977 the eastern portion of the Beltway was re-designated I-95 when a proposed alignment of I-95 from New York Avenue in Washington, DC, through Prince George's County, Maryland to I-495 was cancelled. Motorists never fully adjusted to the two halves of the Beltway having different numbers, so in 1989 the I-495 designation was restored to the eastern portion, making it a dual I-95/I-495.
Traveling clockwise, the Beltway is designated as the Inner Loop; traveling counter-clockwise, it is designated as the Outer Loop.
Traffic volume on the Beltway can be as high as 225,000 vehicles per day. Despite numerous widening projects during its history, heavy traffic on the Beltway is a continuing problem.
Two intersections on the Capital Beltway are ranked in the top 20 on a study of the "worst bottlenecks in the nation." They are the I-495 at I-270 interchange, ranked third overall, which receives 243,425 cars daily and the I-495 at I-95 interchange, ranked 11th, with 185,125 cars. The Springfield Interchange, where I-395, I-95, and I-495 meet, was previously ranked fifty worst in the nation, but recent improvements have taken it off the top 20. Local commuters refer to the Springfield Interchange as "The Mixing Bowl", although this designation is reserved by highway officials for the even more complicated interchange complex adjacent to the Pentagon on the original Henry G. Shirley Memorial Highway (currently better-known as Interstate 395) in Arlington.
Capital Beltway Trivia
Even most local travelers around the entire loop are probably unaware that the circumferential roadway not only is located in the states of Virginia and Maryland, but also crosses briefly through a small portion of the District of Columbia in the Potomac River at the Woodrow Wilson Memorial Bridge. 
The Capital Beltway also interchanges with a "secret" unsigned section of the Interstate Highway System, the long lost Interstate 595 in Maryland, completed in 1995. This roadway is still signed as U.S. Highway 50. 
Originally, the exits in Virginia also were numbered starting with 1, which caused problems because there were some exits that had the same number in Maryland and Virginia. This was changed around 2000 by renumbering all of the low-numbered Virginia exits starting with the next highest number used by the Maryland portion, thus making all exit numbers on the entire beltway unique to both states.
List of Exits
- 2 - Anacostia Freeway (I-295)
- 3 – Indian Head Highway (MD 210)
- 4 – St Barnabas Rd (MD 414)
- 7 – Branch Ave (MD 5)
- 9 – Andrews Air Force Base
- 11- Pennsylvania Avenue (MD 4)
- 13 – Ritchie Rd / Marlboro Rd
- 15 – Central Ave (MD 214)
- 16 – Arena Dr /FedEx Field
- 17 – Landover Rd (MD 202)
- 19 – John Hanson Hwy (US 50) / New Carrollton Metro
- 20 – Annapolis Rd (MD 450)
- 22 – Baltimore – Washington Parkway
- 23 – Kenilworth Ave (MD 201)
- 24 – Greenbelt Metro
- 25 – Baltimore Ave (US 1)
- 27 – I-95
- 28 – New Hampshire Ave [MD 650)
- 29 – University Blvd (MD 193)
- 30 – Colesville Rd (US 29)
- 31 – Georgia Ave (MD 97)
- 33 – Connecticut Ave (MD 185)
- 34 – Rockville Pike (MD 355)
- 35 – I-270
- 36 – Old Georgetown Rd (MD 187)
- 38 – I-270 Spur
- 39 – River Rd (MD 190)
- 40 – Cabin John Parkway
- 41 – Clara Barton Parkway
- 43 – George Washington Memorial Parkway
- 44 – Georgetown Pike (VA 193)
- 45 – Dulles Access Rd / Dulles Toll Rd (VA 267)
- 46 – Chain Bridge Rd (VA 123)
- 47 – Leesburg Pike (VA 7)
- 49 – I-66 (Custis Memorial Parkway)
- 50 – Arlington Blvd (US 50)
- 51 – Gallows Rd (VA 650)
- 52 – Little River Turnpike (VA 236)
- 54 – Braddock Rd (VA 620)
- 57 – I-95 / I-395 (Shirley Memorial Highway)
- 173 – Van Dorn St (VA 401/613)
- 174 – Eisenhower Ave
- 176 – Telegraph Rd (VA 611 / 214)
- 177 – Richmond Hwy / Patrick St (US 1)
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