Interstate 370 Maryland


Interstate 370 in Maryland is a short freeway linking Interstate 270 with the Intercounty Connector (Maryland 200) toll road between Gaithersburg and Rockville. Prior to construction of the ICC, the freeway consisted of a spur to the Shady Grove Metro Station. That connection remains, but is no longer included in the Interstate System and now designated as unsigned Maryland 200A.

The Intercounty Connector extends east from a trumpet interchange with Interstate 370 and Maryland 200A. The 18.8-mile toll road links Gaithersburg and Rockville with Interstate 95 and U.S. 1 near Laurel. The limited access highway uses all electronic toll collection.


AASHTO approved Interstate 370 for the freeway between I-270 and the vicinity of Shady Grove on November 15, 1975. Interstate 370 opened to traffic on December 17, 1988.1 Completion of the Intercounty Connector Project shortened I-370 from 3.13 to 2.54 miles. The truncation to Maryland 200 was conditionally approved by AASHTO on November 16, 2012.

Intercounty Connector

A Draft Environmental Impact Statement (DEIS) was released for the Intercounty Connector project in December 2004, with a toll feasibility analysis completed afterwards.2 The preferred corridor was the southern alignment.3 A Record of Decision was released by the Federal Highway Administration on May 30, 2006.4

Construction on the ICC began in November 2007 after nearly 50 years of debate on whether to build it.5 The ICC was designated as Maryland 200 and is not planned to be designated as Interstate 370.6 Plans called for the six-lane, $2.4 billion tollway to fully open in 2012. The phases for construction were:7

  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 with completion in 2011 or 2012

The ICC fully opened between Interstates 370 and 95 on November 22, 2011. The 1.5 mile extension from I-95 east to U.S. 1 at Laurel opened to traffic on November 10, 2014.

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. Interstate 370 @
  2. "Maryland's ICC may not need any tax money - for Maryland Taxpayers Association," Toll Road News, March 24, 2005.
  3. "Southern Route for Connector Endorsed" Washington Post, February 4, 2005.
  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. "With Obstacles Overcome, Highway Work Begins: Quietly, Barriers and Dirt Emerge at Scattered Sites." Washington Post, November 29, 2007.
  6. "Another Interstate Guide update" by Joe Wolf, Personal Email, 12/17/07.
  7. ICC Project Schedule, accessed on January 2008.

Page Updated April 13, 2016.