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Colorado State Highway 128

State Highway 128 (SH 128) is a 10 mi (16.1 km)[a] long state highway in the Denver, Colorado metro area. SH 128's western terminus is at SH 93 south of Boulder, and the eastern terminus is at Interstate 25 (I-25) in Westminster.

State Highway 128 marker

State Highway 128
Map of north central Colorado with SH 128 highlighted in red
Route information
Maintained by CDOT
Length10.0 mi[1][a] (16.1 km)
Major junctions
West end SH 93 south of Boulder
  SH 121 in Broomfield
US 287 in Broomfield
East end I-25 in Westminster
CountiesBoulder, Broomfield, Adams
Highway system
Colorado State Highways
SH 127SH 131
Going west on SH 128

Route descriptionEdit

The route begins in the west at a junction with SH 93 roughly thirteen miles south of Boulder. From there, the road proceeds eastward into the northern portions of the Denver metropolitan area. The road passes through portions of the cities of Superior, Broomfield, Northglenn, and Westminster and crosses SH 121 before being split by a 3.8 mi (6.1 km) section of concurrency with U.S. Route 287 (US 287) and again resuming its course towards its eastern terminus at exit 223 of I-25 in the city limits of Westminster.

As of 2017 there is a brief gap of much less than a mile between the junction of SH 128 and SH 121 and the junction of SH 121 and US 287 that is not even nominally part of SH 128. This gap is due to be closed in 2018 by a mile-long connector that began construction in 2009;[2] there was a five-year hiatus from 2010 to 2015 during negotiations with BNSF.[3] When construction is complete, the total end-to-end length, including the section that is nominally concurrent with US 287, will be 14 mi (22.5 km).


The route was established in the early 1920s, when it began at Federal Boulevard and ended at SH 185 (now deleted). A section from US 85 to US 6 was added by 1939 and deleted by 1949. The west terminus was extended from US 36 to Indiana Street in 1965 and to its current terminus at SH 93 two years later.[4]

Major intersectionsEdit

Boulder0.0000.000  SH 93 – Arvada, BoulderWestern terminus
City and County of Broomfield7.97312.831    SH 121 (Wadsworth Parkway) to US 36 / US 287
Gap in route
12.16819.582  US 287 (Federal Boulevard)
AdamsThornton14.11322.713  I-25Eastern terminus; exit 223 on I-25
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


^ a: The 3.8 mi (6.1 km) long section of concurrency with US 287 is not maintained with state funds and therefore not considered to be part of SH 128 by the Colorado Department of Transportation.[1]


  1. ^ a b "Segment Descriptions for Highway 128". Colorado Department of Transportation. Retrieved 2008-04-07.
  2. ^ "120th Avenue Connection August 2015 Newsletter". Colorado Department of Transportation. August 2015. Retrieved 8 August 2016.
  3. ^ "Broomfield City Council Manager's Report May 2018". 2018-05-22. Retrieved 2018-08-17.
  4. ^ Salek, Matthew E. "Colorado Routes 120-139". Retrieved 2010-05-30.[self-published source]

External linksEdit