Interstate 270 Maryland

Interstate 270 Maryland
Bethesda, MD ↔ Frederick, MD•34.40 miles

Overview

Interstate 270 in Maryland is a regional connector between the Capital Beltway (I-495) and I-70 at Frederick. A heavily traveled commuter route, I-270 joins Washington, D.C. with points west to Hagerstown and Cumberland and north into Pennsylvania.

Just north of the Capital Beltway, I-270 splits into two branches. The main line angles east to link with I-495 by Chevy Chase. Interstate 270 Spur drops south to join I-270 with I-495 ahead of Cabin John and the American Legion Memorial Bridge across the Potomac River.

North from the merge of I-270 and I-270 Spur, the freeway expands with four overall roadways. The Local / Express configuration extends north to Gaithersburg and MD 117 (Clopper Road) at Exit 10.

Mileage by State

Maryland34.40 mi

Data Sources

December 31, 2021 Interstate Route Log and Finders List

History

The freeway for Interstate 270 was concurrently signed with U.S. 240, an intrastate route from Frederick, Maryland to Washington, DC, from 1960 onward. Interstate 70S was established along the route in 1956 and I-270 subsequently applied to what is now I-270 Spur. I-70 east to Baltimore was designated Interstate 70N.

I-270 - 1968 Maryland Official Highway Map
Interstate 270 was originally the connector joining I-495 with I-70S/U.S. 240 – 1968 Maryland Official Map

U.S. 240 was decommissioned with approval of the American Association of State Highway Officials (AASHO) on June 20, 1972. The Maryland State Highway Administration (MDSHA) determined that the motoring public was orientated to the I-70S signing and that U.S. 240 no longer served any useful purpose. MDSHA followed with a numbering plan to AASHO for approval to eliminate I-70S and I-70N on March 1, 1973:

We are requesting the consideration of the Route Numbering Committee and the concurrence of the Federal Highway Administration in the elimination of the Cardinal Direction suffix letters on Interstate Routes I-70S and I-70N.

It is our understanding that preliminary agreement was reached with Mr. Frank C. Turner, Federal Highway Administration, and your office on the need for the renumbering of these routes to eliminate the postscripts nationwide. In light of this, it is requested that the following route numbers be changed accordingly:

I-70N to I-70 - From the junction of I-270 (formerly I-70S) southwest of Frederick easterly to the junction of I-95 in

Baltimore City

I-70S to I-270 - From the junction of I-70 (formerly I-70N) southwest of Frederick, southeasterly to the junction of I-495 (Capital Beltway) at Pooks Hill

I-270 to I-470 - From the junction of I-270 (formerly I-70S) north of Democracy Blvd., southerly to the junction of I-495 (Capital Beltway)

Washington, DC - 1975 Virginia Official Highway Map
Interstate 470 prematurely added to the Washington, DC inset on the 1975 Virginia Official Highway Map
Frederick inset – 1967 Maryland Official Highway Map
Interstate 70S defaulted onto U.S. 15 north in Frederick prior to the 1960s completion of the freeway west from Frederick to Hagerstown.

The American Association of State Highway and Transportation Officials (AASHTO) Route Numbering Committee concurred with these requests at the meeting held in June 1973. However, in a letter dated February 11, 1974 from AASHTO to MDSHA, the matter of Interstate 470 was questioned:

There is a possibility that you will want to consider not changing the route number of existing I270 between I70S and I495 but rather handling this as a long connection to 270 and handle traffic by appropriate guide signs rather than having a separate interstate route number.

The U.S. Department of Transportation approved the numbering changes of I-70S as I-270 and I-70N as I-70 on March 18, 1975. The FHWA also concurred with the assessment of AASHTO regarding the proposal for Interstate 470:

I-70/270 east split in 1994
Button copy signs preceding the split of I-70/270 eastbound previously referenced Interstate 70S. 02/18/94

We do not approve the renumbering of the existing I-270 as I-470 from its junction with I-495 near Bradley Boulevard northerly to a junction with former I-70S near Tuckerman Lane. Existing I-270 to I-495 and Northern Virginia points and the newly numbered I-270 to I-495 and points in Maryland will be considered a wye (Y) connection of I-270 with I-495.

I-270 Spur was instead established in place of the short I-270 on the west leg connecting with the Capital Beltway.

$27 million in roadwork improved Interstate 270 at MD 187 (Old Georgetown Road) and Rockledge Drive east of I-270 Spur. Work rebuilt the diamond interchange and widened the MD 187 overpass to ten lanes. The project also improved access to Rock Springs Industrial Park with two new ramps from I-270. Despite inclement weather, construction wrapped up nine months ahead of schedule on November 4, 2003 (MDOT, 2003).

North End Interstate 70 U.S. 15 U.S. 40 ‐ Frederick, MD

Interstate 270 North at Interstate 70 U.S. 15 U.S. 40

I-270 north at I-70/US 40 - Frederick, MD

Traffic separates at the north end of I-270 into a two-lane ramp (Exit 32) for Interstate 70 and a two-lane continuation of the freeway to U.S. 40 west. 08/04/13

I-270 north at I-70/US 40 - Frederick, MD I-270 north at I-70/US 40 - Frederick, MD I-270 north at I-70/US 40 - 2002

Interstate 70 East at Interstate 270 U.S. 15 U.S. 40

I-70 east at I-270/US 40 - Frederick, MD

U.S. 15/340 combine along a freeway leading northeast to I-70 at Exit 52 B and U.S. 40 in the city of Frederick. 08/15/21

I-70 east at I-270/US 40 - Frederick, MD I-70 east at I-270/US 40 - Frederick, MD I-70 east at I-270/US 40 - 2006 I-70 east at I-270/US 40 - Frederick, MD I-70 east at I-270/US 40 - Frederick, MD

Interstate 70 U.S. 40 West at Interstate 270 U.S. 15

I-70/US 40 west at I-270/US 15 - Frederick, MD

I-70/U.S. 40 advance west from MD 355 (Market Street) south of Downtown Frederick to their split at I-270 (Exit 53). 06/08/12

I-70/US 40 west at I-270/US 15 - Frederick, MD I-70/US 40 west at I-270/US 15 - Frederick, MD I-70/US 40 west at I-270/US 15 - 2002 I-70/US 40 west at I-270/US 15 - Frederick, MD

South End Interstate 495 ‐ Bethesda, MD

Interstate 270 South at Interstate 495

I-270 south at I-495 - Bethesda, MD

Interstate 270 concludes with ramps joining both the Capital Beltway east toward Silver Spring and MD 355 (Rockville Pike) south to Bethesda. 08/04/13

Interstate 495 West at Interstate 270

I-495 west at I-270 - Bethesda, MD

One mile southeast of the wye interchange (Exit 35) separating I-270 north from I-495 west. 12/30/12

I-495 west at I-270 - Bethesda, MD I-495 west at I-270 - Bethesda, MD I-495 west at I-270 - Bethesda, MD I-495 west at I-270 - Bethesda, MD I-495 west at I-270 - Bethesda, MD

Interstate 270 South at Interstate 270 Spur

I-270/270 Spur south split - Potomac, MD

Southbound on Interstate 270 at the split with I-270 Spur. This is the lone reference on guide signs for the spur route. Photo by Jeff Royston (06/10/06).

Interstate 495 North at Interstate 270 Spur

I-495 east at I-270 Spur - Bethesda, MD

Interstate 495 splits with I-270 Spur 3.6 miles north of the American Legion Memorial Bridge spanning the Potomac River from Virginia. 12/21/12

I-495 east at I-270 Spur - Bethesda, MD I-495 east at I-270 Spur - Bethesda, MD I-495 east at I-270 Spur - Bethesda, MD I-495 east at I-270 Spur - Bethesda, MD

References

Maryland Department of Transportation (MDOT). (2003, November 4). State Highway Administration Celebrates Opening of I-270/MD 187 (Old Georgetown Road)/Rockledge Drive Interchange in Montgomery County. [Press release].
Updated July 21, 2022