Interstate 270 (Maryland)
Interstate 270 (abbreviated I-270) is a spur Interstate highway that travels between the junction with Interstate 70 in Frederick, Maryland and Interstate 495 (the Capital Beltway) just north of Bethesda, Maryland. I-270 also travels through Germantown, Gaithersburg, and Rockville, Maryland. The entire length of I-270 is 34.4 miles. Between Montrose Road and Shady Grove Road, I-270 is 12 lanes; each direction has a four-lane express roadway (including an HOV lane) and a two-lane local roadway.
A spur route, Interstate 370, provides access to a park and ride lot at the Shady Grove station of the Washington Metro.
Interstate 270 divides into two six-lane, bidirectional branches about 2 miles north of its junction with the beltway. For southbound traffic, the eastern (main) branch merges with the inner loop of the Beltway at exit 35, and the western (spur) branch merges with the outer loop at exit 38.
Under the original Interstate numbering system, I-270 was designated I-70S, and the western spur was designated I-270. When I-70S was redesignated I-270, the western spur was known for a short time as Interstate 470, at least on a 1975 Virginia Department of Transportation map. The western spur is now signed and publicly known simply as Interstate 270 Spur, although Maryland State Highway Administration documents refer to it as Interstate 270Y.
A proposal to extend I-270 inside the Beltway into Washington, D.C., was canceled because of community opposition.
According to the "Master Plan", another exit from I-270 will occur less than a mile north of current exit 26 to Maryland Route 80. The plan calls for an interchange onto Park Mills Road to accommodate the quickly expanding Urbana region.
The proposed Intercounty Connector would connect I-270 from the I-370 spur to I-95 near Laurel.
Control cities
The following cities are officially designated control cities for signs:
Exit list
Exits are numbered from south to north, in accordance with AASHTO guidelines.
| # | Destinations | Notes |
|---|---|---|
 Interstate 495 east - College Park; Silver Spring
|
southbound exit and northbound entrance | |
 Maryland Route 355 south - Bethesda
|
southbound exit and northbound entrance | |
| 1 |  Maryland Route 187 - Old Georgetown Road; Rockledge Drive
|
split into 1A (MD 187) and 1B (Rockledge Drive) northbound |
| Interstate 270 Spur to Interstate 495 south - Washington, DC; Northern Virginia | southbound exit and northbound entrance | |
| 4 | Montrose Road | split into 4A (east) and 4B (west) |
| 5 |  Maryland Route 189 - Falls Road
| |
| 6B-A |  Maryland Route 28 - West Montgomery Avenue; Rockville; Darnestown
|
split into 6A (east) and 6B (west) northbound |
| 8 | Shady Grove Road | |
| 9 |  Interstate 370 - Metro Station; Sam Eig Highway
|
split into 9A (east) and 9B (west) |
| 10 |  Maryland Route 117 to Maryland Route 124 west - Clopper Road; West Diamond Avenue; Quince Orchard Road
|
northbound exit and southbound entrance |
| 11 |  Maryland Route 124 east - Montgomery Village Avenue
|
northbound exit and southbound entrance |
| 11 | Maryland Route 124 - Quince Orchard Road; Montgomery Village Avenue
|
southbound exit and northbound entrance |
| 13 | Middlebrook Road | northbound exit and southbound entrance; split into 13A (east) and 13B (west) |
| 15 |  Maryland Route 118 to Maryland Route 355 - Germantown
|
split into 15A (north) and 15B (south) northbound |
| 16 | to Maryland Route 27 - Father Hurley Boulevard; Damascus | |
| 18 |  Maryland Route 121 - Boyds; Clarksburg
| |
| 22 |  Maryland Route 109 - Hyattstown; Poolesville
| |
| 26 |  Maryland Route 80 - Urbana; Buckeystown
| |
| 31 |  Maryland Route 85 - Market Street; Frederick; Buckeystown
|
split into 31A (north) and 31B (south) |
| 32 |   Interstate 70 - Hagerstown; Baltimore (U.S. Route 40 east)
| |
 U.S. Route 15 - Frederick; Gettysburg, PA (U.S. Route 40 west)
|
northbound exit and southbound entrance |
