Interstate 235 Iowa
Interstate 235 forms an urban loop from West Des Moines east to Downtown Des Moines, then north to unincorporated Polk County and Ankeny. I-35/80 bypass the capital city to the north, but along a suburban route through Clive, Urbandale and by the cities of Grimes and Johnston.
Heading east from the merge of I-35 and I-80 (West Mixmaster Interchange) through West Des Moines, I-235 travels below grade with six overall lanes and auxiliary lanes to 22nd Street. Crossing Walnut Creek, the freeway straddles the south city limits of Windsor Heights to Iowa 28 and Des Moines. Sound walls line portions of the route east as I-235 expands to eight lanes.
Staying below grade, Interstate 235 increases to ten lanes in width with auxiliary lanes as it crosses northern reaches of Downtown Des Moines by Mercy Medical Center. While approaching the Des Moines River, the freeway reduces to six lanes as it begins the northern turn toward Ankeny. The state capitol appears just south of I-235 by Exit 9 with U.S. 65.
Sound walls again line the freeway right of way northward from Iowa 163 to the return of I-35/80. Within the East Mixmaster Interchange, the freeway mainline defaults motorists onto I-35 north toward Ames, Mason City and Minneapolis while the original roadway serves movements back west to Johnston and east along I-80 to the Quad Cities.
An outer loop for Des Moines was constructed from south West Des Moines east around Des Moines to Carlisle, Pleasant Hill and Altoona. Completed in 2002, the freeway is designated Iowa 5 along the south leg and as part of U.S. 65 from U.S. 69 north to Interstate 80 along the east leg. Several communities along the bypass pushed to have the loop designated as an Interstate in 2012. Precluding the upgrade however is the use of the route by slow moving farm machinery, as such vehicles are prohibited from using Interstate highways. Additionally the freeway is not set with a minimum speed.1 A 2014 story from Iowa Public Radio indicates that more time will be allowed to study the possibility of upgrading the route.2
Source: December 31, 2021 Interstate Route Log and Finders List
The original design of Interstate 235 included roadway splits at Keosauqua (Keo) Way west of the Des Moines River and at University Avenue. The separations accommodated left entrance ramps.
I-235 Annual Average Daily Traffic (AADT)
Source: Traffic Flow Map of Des Moines – 2016 AADT – Iowa Department of Transportation
Traffic Flow Map of West Des Moines – 2016 AADT – Iowa Department of Transportation
The Des Moines City Council voted 5-0 in support of the freeway plan for Interstate 235 in 1957. That same year, the Federal Bureau of Public Roads gave final approved to the Iowa Highway Commission to build the route. Costs were estimated at $54,763,000 for construction on the first urban freeway project in Iowa.3
Preliminary design work was completed in 1958, indicating that the route would serve area needs through 1978. Right of way purchases totaled $21,078,000, with five hundred acres acquired including 1,100 dwelling units, 50 businesses, three schools and two churches. The freeway was designed for 50 mile per hour speeds.3
Interstate 235 was designated the John MacVicar Freeway in the 1960s by the Des Moines City Council. John MacVicar was mayor of the city from 1896 to 1900 and again from 1916-18. He also served stints as streets commissioner and public safety commissioner and mayor for a third time in 1928 before his death. His son, also named John MacVicar, held the position of streets commissioner twice to 1940 and as mayor from 1942 to 1950. He passed away in 1950.3
The first portion of I-235 opened was the 1.2 mile long section from Cottage Grove Avenue to 12th Street, including the bridges across the Des Moines River. This stretch took three years to build and cost $9.5 million. Further north, the exchange between I-35, I-80 and I-235 was nicknamed the [East] “Mixmaster” by highway engineers in 1961, due to the intricate nature of its design.3 The junction between I-35, I-80 and I-235 in West Des Moines was nicknamed the West Mixmaster Interchange.
Early design elements of Interstate 235 called for bridge clearances of 14.5 feet, instead of the recommended 16 foot clearance to accommodate the movement of military equipment. The reduced height meant that military traffic was routed around Des Moines to offset the cost with raising overpasses and their approaches.3
Construction on Interstate 235 was completed in 1968, four years ahead of schedule.3 Segments of the MacVicar Freeway opened as follows from west to east:4
- I-35/80 east to 63rd Street: October 30, 1968
- 63rd Street to 31st Street: December 6, 1967
- 31st Street to Cottage Grove Avenue: December 13, 1966
- Cottage Grove Avenue to Keo Way: December 14, 1961
- Keo Way to Penn Avenue: November 9, 1963
- Penn Avenue to Easton Boulevard: December 13, 1966
- Easton Boulevard to I-35/80 (Mixmaster interchange): December 6, 1967
All of Interstate 235 was reconstructed to modern design standards during the $429 million Rebuilding I-235 project underway from March 2002 to 2007. Construction replaced all low clearance bridges, expanded the freeway to at least six lanes in width, lengthened exit and entrance ramps and added lighting and landscaping.
Three steel pedestrian bridges were added at 44th, 40th and E 6th Streets. The basket-handle arch bridges replaced preexisting structures. The span design celebrates the arched river bridges that are symbolized in the city logo. The Edna M. Griffin Memorial Bridge near East 6th Street was completed in January 2004. The 40th and 44th Street bridges were constructed from October 2004 to Fall 2005.
Interchange modifications outlined on the Rebuilding I-235 project web site:
- West West Drive Interchange – March 2003 to November 2003
A new eastbound entrance ramp was added from Valley View Drive north. Ramps along I-235 were were realigned further south and the Valley View Drive overpass was replaced.
- 56th Street Interchange – May to December 2005
The 56th Street overpass was replaced and the loop ramp from southbound to I-235 east was removed.
- 42nd Interchange – March to August 2004
The interchange was reconstructed with a new bridge built over I-235.
- 35th, 31st, 28th Streets – March to December 2005
A diamond interchange replaced the eastbound off-ramp to 35th Street and a loop ramp from 31st Street south to I-235 east. Bridges for I-235 over 35th and 28th Street were replaced, as was the 31st Street overpass.
- MLK, Jr. Parkway, 19th Street, Cottage Grove Avenue – March 2002 to March 2004
Cottage Grove Avenue was realigned onto a new overpass in conjunction with a new eastbound off-ramp to School Street in 2002. New ramps were added from both the new 19th Street bridge and MLK, Jr. Parkway to southbound. The split directions of Cottage Grove Avenue and its associated ramp system to I-235 were demolished.
- Keo Way Interchange – September 2004 to Summer 2007
Keo Way was reconstructed below I-235 while new off-ramps were completed. The service roads connecting I-235 with Keo Way and 19th Street take the place of the former freeway mainline, which previously separated to accommodate left-hand ramps along eastbound to and from Keo Way. A new on-ramp to I-235 was also completed, which passes below the new off-ramp to 7th and 3rd Streets. The loop ramp on the southeast quadrant with Keo Way was removed as well.
- 2nd Avenue / 3rd Street Interchange – September 2002 to December 2003
Overpasses for 2nd Avenue, 3rd Street and 5th Avenue were replaced and ramps reconstructed. The 12th Street on-ramps, which joined the left side of both directions of Interstate 235, were permanently removed.
- 5th Avenue, 6th Avenue, 7th Street Interchange – July 2004 to Summer 2005
New bridges for all three numbered streets. The curved overpass for 5th Avenue was removed and 5th Avenue was made continuous north of Day Street.
- E 6th Street, Pennsylvania Avenue Interchange – April 2003 to December 2003
New bridges were built for East 6th and 9th Streets in 2002. Redesign of the interchange consolidated back to back off-ramps into a wider split-diamond interchange.
- E 14th and 15th Street Interchange – March 2004 to December 2005
Collector distributor roadways added between 12th and 14th Streets as part of interchange reconstruction.
- East University Avenue to Guthrie Avenue – June 2002 to November 2003
A new westbound roadway was constructed for I-235, replacing the westbound ramps to and from Easton Boulevard.
- East University Avenue and Easton Boulevard – January 2004 to spring 2006
The split roadways of Interstate 235 were realigned to eliminate left entrance ramps from Iowa 163. Ramps along I-235 east to Easton Boulevard were rebuilt, while the separate sections of Easton Boulevard below the freeway were linked.
- East Euclid Avenue Interchange – November 2002 to December 2003
The U.S. 6 overpass was replaced and the loop ramp from I-235 north to Euclid Avenue was removed.
Construction following the Rebuild I-235 project in 2007-09 addressed some of the left side ramps at the East Mixmaster interchange. A new set of roadways was built to seamlessly link Interstate 235 to the south with I-35 to the north. The former north and southbound lanes were repurposed as distributor roadways for the exits from I-35 south and I-235 north. Left exit ramps remain in place from I-80 west to I-235 south and at the northbound split of I-35 from I-80 east.
East End – Des Moines, Iowa
Interstate 235 extends south from I-35 with two lanes into Des Moines as traffic separates for Left Exit 137A to I-80 east and the continuation of I-35/80 to Johnston and Urbandale. 02/21/20
North East at
I-35 and I-80 split for Ames and Iowa City respectively at the East Mixmaster Interchange with Interstate 235. 03/28/16
East End Throwback
North East at
West End – Des Moines, Iowa
South West at
Exit 72A loops away from Interstate 35 south to I-235 east back toward Des Moines. Drivers continuing south remain within West Des Moines to the Madison County line. Suburban areas spread south along the freeway to the Raccoon River. 02/21/20
Interstate 80 curves east through a six-ramp parclo interchange (Exit 121) with Jordan Creek Parkway on the one mile approach to the West Mixmaster Interchange (Exit 123) with I-35 and I-235 east.
This diagrammatic sign was replaced with a sign using Clearview font by 2015 with West Des Moines was dropped as a control city. Photo by Jeff Morrison (08/19/04).
The mainline continuation of the I-80 freeway at the East Mixmaster Interchange is assigned Exit 123A as I-80 turns north via a two-lane directional ramp to combine with I-35.
This diagrammatic sign was replaced by 2015 to include a Left Exit tab for 123A. Photo by Jeff Morrison (08/19/04).
Motorists bound for Interstate 35 south to Kansas City depart in unison with the I-80 northward turn to Clive, Urbandale and Johnston.
This set of signs was replaced by 2015 with West Des Moines omitted. The capital city suburb was dropped from signs along I-80, as the municipal limits annexed areas westward to Ashworth Road. Photo by Jason Hancock (03/99).
Button copy signs posted at Exits 123A/B referenced Interstate 235 east on a pull through panel. Photo by Michael Summa (1979).
South West at
- “Problems noted in beltway plan.” Des Moines Register, November 21, 2012.
- “Iowa’s Newest Interstate?” Iowa Public Radio, October 3, 2014.
- “I-235 Unearthing The Past.” Rebuilding I-235 project web site.
- “Iowa Completion Status of Interstate System as of January 1, 1982.” Iowa Department of Transportation.
Updated November 4, 2020.