&sq=&lang=&file=File:I-270.svg) Interstate 270 | ||||
|---|---|---|---|---|
| Dwight D. Eisenhower Highway Washington National Pike | ||||
 I-270 highlighted in red; I-270 Spur in blue | ||||
| Route information | ||||
| Auxiliary route of I-70 | ||||
| Maintained by MDSHA | ||||
| Length | 34.70 mi[1] (55.84 km) | |||
| Existed | 1975–present | |||
| NHS | Entire route | |||
| Major junctions | ||||
| South end |   I-495 / MD 355 in Bethesda | |||
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| North end |   I-70 / US 40 in Frederick | |||
| Location | ||||
| Country | United States | |||
| State | Maryland | |||
| Counties | Montgomery, Frederick | |||
| Highway system | ||||
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Interstate 270 (I-270) is a 34.7-mile (55.8 km) auxiliary Interstate Highway in the U.S. state of Maryland that travels from I-495 (Capital Beltway) just north of Bethesda in Montgomery County north to I-70 in the city of Frederick in Frederick County. It consists of the 32.6-mile (52.5 km) mainline as well as a 2.1-mile (3.4 km) spur that provides access to and from southbound I-495. I-270 is known as the Washington National Pike, and makes up the easternmost stretch of the Dwight D. Eisenhower Highway.[3] Most of the southern part of the route in Montgomery County passes through suburban areas around Rockville and Gaithersburg that are home to many biotech firms. This portion of I-270 is up to 12 lanes wide and consists of a local–express lane configuration as well as high-occupancy vehicle lanes (HOV lanes) that are in operation during peak travel times. North of the Gaithersburg area, the road continues through the northern part of Montgomery County, passing Germantown and Clarksburg as a six- to eight-lane highway with an HOV lane in the northbound direction only. North of here, I-270 continues through rural areas into Frederick County and toward the city of Frederick as a four-lane freeway.
The freeway was built between 1953 and 1960 as the Washington National Pike between Bethesda and Frederick and carried U.S. Route 240 (US 240), which was rerouted off what is now Maryland Route 355 (MD 355) between these two points. With the creation of the Interstate Highway System a few years later, the road was designated as I-70S along with US 240. There were plans to extend I-70S to I-95 in Washington, D.C., on the North Central Freeway from the Capital Beltway; however, they were canceled in the 1970s due to opposition from residents in the freeway's path. The concurrent US 240 designation was removed in 1972 and I-70S became I-270 in 1975. Increasing traffic levels led to a $200-million (equivalent to $496 million in 2023[4]) widening of the road in Montgomery County to its current configuration. Many improvements are slated for I-270, including the widening of the route that would add high-occupancy toll lanes (HOT lanes).
- ^ "Route Log — Auxiliary Routes of the Eisenhower National System Of Interstate and Defense Highways — Table 2". Federal Highway Administration. October 31, 2002. Retrieved May 13, 2009.
- ^ a b Highway Information Services Division (December 31, 2013). Highway Location Reference. Maryland State Highway Administration. Retrieved March 2, 2012.
- Montgomery County (PDF).
- Frederick County (PDF).
- ^ "Dwight D. Eisenhower Highway". Retrieved April 5, 2015.
- ^ Johnston, Louis; Williamson, Samuel H. (2023). "What Was the U.S. GDP Then?". MeasuringWorth. Retrieved November 30, 2023. United States Gross Domestic Product deflator figures follow the MeasuringWorth series.