Interstate 270 Colorado
Overview
Interstate 270 angles northwest from I-70 by the Stapleton community in Denver through Commerce City to I-25 by a commerce park area at Welby in southern Adams County. The freeway serves commuters west to Westminster and Boulder via connections with U.S. 36, and northeast Denver and Aurora beyond the east end with I-70.
The freeway accommodates six lanes of traffic between I-25 and I-76, and just four southeast to I-70. Together with Interstate 76 west to Arvada and Wheat Ridge, I-270 provides a bypass of the oldest section of I-70 through north Denver.
History
Preliminary numbering for I-270 connecting I-80S (now I-76) and Stapleton International Airport identified it as part of Route A25, a circumferential highway around the east side of Denver along with what became I-225. Communication between the Colorado Department of Highways and the American Association of State Highway Officials (AASHO) in 1958/59 resulted in subsequent suggestions. The first proposal renumbered I-A25 as I-E25, as it would provide an eastern bypass for Interstate 25.
The Colorado Department of Highways then outlined partitioning I-25E into I-225 for the loop south from I-70 through Aurora, and I-425 for the connection northwest from I-70 to I-25 via Commerce City. The designation changed to Interstate 270 once the planned west end of I-80S was changed from a point along I-70 in Denver northward to I-25 over the westernmost section of I-425. This was approved by AASHO on February 26, 1959.1
Construction of the freeway began on December 12, 1965, with $2.7 million in projects including bridges over Dahlia Street, the Quebec Street overpass, and spans for I-270 over Interstate 70. The initial three miles opened to traffic northwest from I-70 to Vasquez Boulevard (U.S. 6-85). Further work on the two mile link between U.S. 6-85 and I-80S followed with completion on October 23, 1970.2
Construction on the extension west to U.S. 36 (Boulder-Denver Turnpike) and Interstate 25 started in April 1993. Coupled with work to lengthen I-76 from I-25 to Pecos Street, Phase I built an eastbound bridge for I-270 over I-25 and rebuilt the U.S. 36 east to I-25 north and southbound ramps. The $11.4 million phase was completed in June 1994. Subsequent construction started in June 1996 for the westbound I-270 bridges over Washington Street and I-25, and a bridge connecting I-25 north with U.S. 36 west. That construction ran through May 1998 and cost $12 million.2
Costing $12 million, additional work from July 1997 to December 1998 built the I-270 westbound bridge over Clear Creek with associated construction for U.S. 36 over Broadway and the I-25 southbound ramp to U.S. 36 west. The westbound extension of Interstate 270 was completed in February 2000 as part of an $19 million improvement project for I-25 and U.S. 36 from June 1998 to June 2001.2 The American Association of State Highway and Transportation Officials (AASHTO) Route Numbering subcommittee approved extending Interstate 270 northwest from I-76 to I-25 on April 7, 2000.
Route Information
East End – Denver, CO
West End – Commerce City, CO
Mileage – 6.61
Cities – Denver, Commerce City
- Junctions –
Source: December 31, 2021 Interstate Route Log and Finders List
Short segments of I-80S, I-225 and I-270 were opened to traffic across the Denver metropolitan area by 1968.
The original configuration of Interstate 270 in 1986. Exit numbers along the freeway remain unchanged today, despite the addition of one mile.
Further east on the original section, the bridges over U.S. 6-85 (Vasquez Boulevard) were replaced from March 1999 to June 2000 at the cost of $6.2 million. $8.5 million in concurrent work completed the eastbound lanes of I-270 from I-25 to York Street from October 1999 to March 2002. The trumpet interchange joining I-76 and I-270 was also upgraded through a series of projects. $21 million in work between June 2000 and August 2003 rebuilt ramps from I-270 to both directions of I-76, and constructed seven spans at the exchange.2
A new flyover was added from Interstate 25 south to I-270/U.S. 36 east as part of an overall I-25 reconstruction project between 84th Avenue and I-76. The $21 million project ran from March 2004 to November 2005. A $15 million flyover project added the movement from I-270 east to I-76 east.2
Highway Guides
East End 
– Denver, Colorado
East at
Interstate 270 converges with I-70 east at a wye interchange within the Central Park neighborhood in northeast Denver. Exit 5 separates from the freeway end for Central Park Boulevard. 08/11/16
An end Interstate 270 shield stands above the departing off-ramp (Exit 279) from I-70 east to Central Park Boulevard. 08/11/16
Two lanes of traffic merge onto I-70 east below Central Park Boulevard. The exchange here opened in October 2011. Central Park Boulevard serves the residential redevelopment of what was Stapleton International Airport. 08/11/16
West at
Interstate 70 advances west from I-225 and the Montbello neighborhood in Denver to Central Park and I-270 at Exit 279A. 04/22/17
The diamond interchange joining I-70 with Central Park Boulevard at Exit 279B overlays the wye interchange (Exit 279A) with I-270 west. 04/22/17
Two lanes separate from I-70 west for Interstate 270 and U.S. 36 to Commerce City, Westminster and Boulder. I-270 provides a cutoff to I-25 north for Fort Collins and Cheyenne, Wyoming. 04/22/17
East End Throwback
Nearing the merge point with Interstate 70 east on I-270 prior to construction of the interchange with Central Park Boulevard. I-70/U.S. 36 continues east to Havana Street in industrial areas of Stapleton at Exit 280. Photo by Dale Sanderson (04/01).
Construction of Central Park Boulevard (Exit 279B) changed the traffic pattern along I-70 west to I-270 by 2011. Exit 279A for I-270 west departs where this advance sign was located. 02/03/02
Westbound I-70 previously split with I-270 at Exit 279. Traffic to I-270 west now combines with an entrance ramp from Central Park Boulevard before turning north ahead of Quebec Street (former SH 35). Photo by Dale Sanderson (04/01).
West End – near Commerce City, Colorado
West at
Interstate 270 west connects with I-25 north two miles west of the SH 265 (Brighton Boulevard) underpass. There is no direct connection to I-25 south; instead motorists are directed onto I-76 west for its exit to Denver. 04/22/17
Crossing the South Platte River, I-270 advances from Commerce City to meet Interstate 76 at Exit 1. 04/22/17
Interstate 270 was extended west from the cloverstack interchange with I-76 to I-25 in 2000. 08/11/16
Exit 0 joins I-270 west with Interstate 25 north to Thornton, Northglenn and other northern Denver suburbs. Parallel SH 224 ties into U.S. 36 at Broadway. 08/11/16
The completion of Interstate 270 provided a seamless link for U.S. 36 west to the Denver-Boulder Turnpike. Previously U.S. 36 navigated west on I-76 and north on I-25 to continue northwest to Boulder. 08/11/16
U.S. 36 emerges from the hidden overlap with I-270 at the systems interchange with Interstate 25. The Boulder-Denver Turnpike takes U.S. 36 northwest to Westminster, Broomfield, Louisville and Superior. 08/11/16
East at
The Denver-Boulder Turnpike along U.S. 36 originates at Boulder, 20 miles to the northwest of the exchange joining I-25/270. U.S. 36 east transitions onto I-270 east beyond I-25. 04/23/17
An exit ramp leaves U.S. 36 east for Broadway to SH 225 just ahead of the three level interchange with I-25 and I-270 east. 04/23/17
I-25 south previously linked U.S. 36 (Denver-Boulder Turnpike) east with Interstate 76 east. A direct connect flyover joins I-270/U.S. 36 with I-76 directly in 0.75 miles. 04/23/17
A begin shield for Interstate 270 east appears at the loop ramp (Exit 0) for I-25 north toward Fort Collins. 08/11/16
South at
Interstate 25 travels south toward I-270 east and U.S. 36 (Denver-Boulder Turnpike) west through the city of Thornton. 04/23/17
I-270/U.S. 36 east connects I-25 south with Interstate 76 east toward Fort Morgan. 04/23/17
Left Exit 217B for I-270 east is also accessible from the tolled Express Lanes along Interstate 25 southbound. 04/23/17
A two lane flyover joins I-270 east ahead of Interstate 76 and Commerce City. Exit 217A links with U.S. 36 (Denver-Boulder Turnpike) northwest to Westminster. 04/23/17
West End Throwback
West at
CDOT inventories only one route on implied concurrences. U.S. 36 along I-70 west from Strasburg to Denver and on I-270 is factored into the mileage of the respective Interstate highway. The Denver-Boulder Turnpike is a part of Route 036B, which is the second independent stretch of U.S. 36 inventoried in the state. Photo by Dale Sanderson (04/01).
East at
Until March 2002, Interstate 270 began at I-76 (Exit 6). Work at the former trumpet interchange between the two freeways continued through August 2003. Photo by Dale Sanderson (04/01).
West at
Approaching Interstate 270 and U.S. 36 on I-76 westbound. Signs still referenced the western extension of I-270 as a Future route. 02/03/02
Sources:
- Summers, Stephen “Interstate Numbering AASHTO and FHWA.” Online posting. April 18, 2003. news misc.transport.road.
- Interstate 270 – 50th Anniversary of the Interstate System. Colorado Department of Transportation (CDOT).
Page updated November 12, 2020.
