Interstate 370 Maryland


Interstate 370 in Maryland is a very short freeway linking Interstate 270 with the Shady Grove metro station northwest of Washington, D.C., in Gaithersburg.

High Priority Corridor

The proposed 18.8-mile Intercounty Connector (ICC), which would link Interstate 370 with Interstate 95 and U.S. 1 is part of High Priority Corridor 80.

Future Aspirations

Interstate 370 is planned to connect with the proposed Intercounty Connector. The proposed 18.8-mile Intercounty Connector (ICC), which would link Interstate 370 with Interstate 95 and U.S. 1 to the east began construction in November 2007 after nearly 50 years of debate on whether to build it.6 The ICC is part of High Priority Corridor 80. The ICC will be designated as Maryland 200 once it is complete; it is not planned to be designated as Interstate 370.7 Plans call for the six-lane, $2.4 billion tollway to fully open in 2012. The phases for construction are:8

  1. Contract A - connects Interstate 370 and Maryland 97/Georgia Avenue (7.2 miles, construction from 11/13/07 to Fall 2010; $478.7 million cost)
  2. Contract B - connects Maryland 97/Georgia Avenue with U.S. 29 (7.0 miles, construction from Mid-2008 to Late 2011; up to $460 million cost)
  3. Contract C - connects U.S. 29 with Interstate 95 (3.7 miles, construction from 1/14/08 to Late 2011, $513.9 million)
  4. Contract D - constructs collector-distributor roadway system between ICC and Interstate 95 (three miles at a cost up to $75 million) - construction begins in 2010 and completes in 2011 or 2012

Once constructed, the connector would be managed by the Maryland State Highway Administration (SHA) as a toll facility. Even though adamant opposition has often delayed this major project (see Montgomery Intercounty Connector Coalition Inc. for the opposing view), construction began in November 2007.

A Draft Environmental Impact Statement (DEIS) was released for the project in December 2004, and a toll feasibility analysis is currently underway to determine if projected proceeds would pay for the cost of the project.1 The preferred corridor is the southern alignment.2 A Record of Decision was released by the Federal Highway Administration on May 30, 2006.4

Approximately one-third of the funding for the ICC project will be paid by the implementation of tolls. Toll rates will be dependent on how many motorists will use the six-lane limited-access highway. Rates may also be adjusted throughout the day, with higher rates during peak travel times. These variable toll rates will aid in the traffic flow of the highway and generate between $400 to $600 million in potential funds to pay off bonds. Additionally $1 billion may be financed through bonds covered by federal highway money allocated to the state over the next 30 years. Gov. Robert L. Ehrlich Jr. (R) indicates that the Intercounty Connector is one of his top transportation priorities and feels that tolls are a viable option.

The connector is planned as a freeway, and interchanges are planned at the following locations: Junction Maryland 355, Shady Grove Road (including Metrorail Access), Junction Maryland 97/Georgia Avenue, Junction Maryland 182/Layhill Road, Junction Maryland 650/New Hampshire Avenue, Junction U.S. 29/Briggs Chaney Road, Junction Interstate 95, Virginia Manor Road, and an at-grade intersection with U.S. 1.4 The 18-mile freeway is planned for construction in 2007 and completion in 2012.3, 6 Of the total 18 miles, 16 miles would be in Montgomery County and the remaining two miles would be located in Prince George's County.4, 5


Interstate 370 opened to traffic in August 1989.9

Highway Guides

Western Terminus - Interstate 270 - Gaithersburg, Maryland
Perspective from Interstate 370 west
Traveling west on Interstate 370 near the western terminus is this Interstate 270 and Interstate 370 ENDS overhead sign near the Interstate 270/370 interchange. This marks the western end of Interstate 370. The Fields Road interchange, on the west side of Interstate 270, is not part of Interstate 370. Photo taken 10/01.
Perspective from Interstate 370 east
This is the first reassurance shield along eastbound Interstate 370. Photo taken by Jeff Royston (06/10/06).
Immediately after the Fields Road intersection, Interstate 370 begins its eastward journey. This Interstate 270 sign bridge is found after Fields Road on the beginning of east Interstate 370. The overpass above was originally an at-grade intersection and was converted to freeway standards. Photo taken by Jeff Royston (06/10/06).
Perspective from Interstate 270 north
Northbound Interstate 270 Local at Interstate 370. Interstate 370 actually does not proceed west of here, based on the ends overhead in the above photograph. However, the limited access section does continue to the junction with Maryland 119. Photo taken by 01/02/01.
Eastern Terminus - Park and Ride - east of Gaithersburg, Maryland
Perspective from Interstate 370 east
Black/White END Interstate 370 advisory sign; this was a new sign in 2001. These signs are common in Virginia, but now are being used in Maryland and other states. Photo taken by 01/02/01.
END Interstate 370 shield before the entrance to the Metro Station. This marks the eastern terminus of Interstate 370. Photos taken by 01/02/01 and Jeff Royston (06/10/06).
Perspective from Interstate 370 west
First Interstate 370 shield on Westbound, posted at the exit of the Metro station. This sign shows that the primary function of Interstate 370 is to take commuters to Interstate 270. That will change if Interstate 370 is extended. The backside of the End Interstate 370 shield is visible to the left. Photo taken 10/01.


  1. Maryland's ICC may not need any tax money - for Maryland Taxpayers Association, Toll Road News, March 24, 2005.
  2. Southern Route for Connector Endorsed from the Washington Post on February 4, 2005 by Katherine Shaver. (A map of the ICC is included via the link.)
  3. "Road Plan Includes Tolls." The Washington Post, September 10, 2003.
  4. Posts from misc.transport.road newsgroup: "Maryland ICC Record of Decision and Groundbreaking" by Scott M. Kozel, 05/31/06 and "Re: Maryland ICC Record of Decision and Groundbreaking" by Scott M. Kozel, 05/31/06.
  5. NEW TOLLROAD: Maryland's ICC groundbreaking, Toll Road News, 05/30/06.
  6. With Obstacles Overcome, Highway Work Begins: Quietly, Barriers and Dirt Emerge at Scattered Sites by Katherine Shaver, Washington Post, November 29, 2007.
  7. "Another Interstate Guide update" by Joe Wolf, Personal Email, 12/17/07.
  8. ICC Project Schedule, which includes a map and schedule as of January 2008
  9. Interstate 370 @

Page Updated April 16, 2008.

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State Maryland
Mileage 2.54
Cities Gaithersburg
Junctions Interstate 270
Source: December 31, 2015 Interstate Route Log and Finders List
I-370 Maryland Annual Average Daily Traffic

County From: To: AADT Composite
-- -- -- --
Montgomery Interstate 270 Maryland 355/Shady Grove Road 77,775
Source: 2002 AADTS Report (Maryland Department of Transportation State Highway Administration - Highway Information Services Division)