Interstate 370 (I-370) is a 2.54-mile (4.09 km) Interstate Highway spur route off I-270 in Gaithersburg, Maryland, to the western end of the Maryland Route 200 toll road at an interchange that provides access to the park and ride lot at the Shady Grove station on the Red Line of the Washington Metro. Despite the number, I-370 does not connect to I-70 itself. The road continues to the west of I-270 as Sam Eig Highway, a surface road. Along the way, I-370 has interchanges with MD 355 and Shady Grove Road. The freeway was completed in the late 1980s to connect I-270 to the Shady Grove station. I-370 was always part of the planned Intercounty Connector but was the only segment to be built at the time. The opening of MD 200 east of I-370 resulted in the truncation of I-370 to the interchange with MD 200 and the redesignation of the road leading into the Shady Grove station as MD 200A.

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 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. 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 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.