Iowa Highway 12

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Iowa Highway 12

Iowa 12 highlighted in red
Route information
Maintained by Iowa DOT
Length46.212 mi[1] (74.371 km)
Loess Hills Scenic Byway
Major junctions
South end US 20 / US 75 at Sioux City
Major intersections
North end Iowa 10 in Hawarden
CountryUnited States
Highway system
Iowa 10 Iowa 13

Iowa Highway 12 (Iowa 12) is a 46.212-mile-long (74.371 km) state highway that runs from north to south in northwestern Iowa. The highway begins in eastern Sioux City at U.S. Highway 20 (US 20) and US 75. For the first seven and a half miles (12.1 km) of the route, Iowa 12 is an unsigned highway. The first five miles (8.0 km) are signed only as U.S. Highway 20 Business; the other two and a half miles (4.0 km) are overlapped by Interstate 29 (I-29). From here, the highway lies just east of the Big Sioux River, which separates Iowa from South Dakota. The northern end of Iowa 12 is in Hawarden at an intersection with Iowa 10.

Route description

Stone State Park is along Iowa 12

Iowa Highway 12 begins at U.S. 20 and U.S. 75 signed as Business US 20. It continues west through Sioux City and becomes concurrent with Interstate 29 going west to Riverside Boulevard, where signage begins. It follows Riverside Boulevard while it passes through the Riverside neighborhood in Sioux City. It passes past Stone State Park in northwestern Sioux City and continues northwest towards Westfield. It turns northeast to enter Westfield, then intersects Iowa Highway 3. Iowa 12 and Iowa 3 overlap and go northeast to Akron, where Iowa 3 turns east. Iowa 12 continues northeast through Chatsworth and ends at Iowa 10 in Hawarden.


Iowa Highway 12 was designated as a state highway in 1920. It originally went between Hamburg and Akron. It was shortened to Missouri Valley in 1924, and Sioux City in 1926. In 1931, it was extended north to Hawarden. In 1958, it was shortened to its intersection with I-29, but then in 1979, was extended east along I-29 and the newly formed Business Route 20 to end at the new U.S. 20 bypass in eastern Sioux City. In 2000, signage for this extension was removed and signage for Iowa 12 ended at I-29, though officially, Iowa 12 continues east through Sioux City.

Major intersections

township line

US 20 Bus. begins / US 20 / US 75 – South Sioux City
Southern end of US 20 Business overlap; US 75 south exit 93, US 20 east exit 4B
Sioux City3.0854.965Fairmount StreetFormer US 75
US 75 Bus. (Lewis Boulevard)
I-29 south
Southern end of I-29 overlap; exit numbers follow I-29; signed exit 147 southbound
US 77 south (US 20 Business west) / Wesley Parkway north – South Sioux City, Nebraska
Southern end of US 20 Business overlap; southbound access via exit 149

To US 77 south (US 20 Business west) / Hamilton Boulevard – Riverfront
Wesley Parkway north – South Sioux City
Northbound signed as Hamilton Boulevard only
I-29 north – Sioux Falls
Northern end of I-29 overlap; IowaDOT signs this as southern end of Iowa 12
8.15513.124War Eagle DriveFormer US 77
9.90915.947Military RoadFormer US 77
PlymouthWestfield Township28.69846.185
Iowa 3 west – Vermillion, S.D.
Southern end of Iowa 3 overlap
Iowa 3 east (South Street) / Loess Hills Scenic Byway ends – Le Mars
Northern end of Iowa 3 overlap

Big Sioux River Road to I-29 / SD 48 – Alcester
SiouxHawarden46.55174.917 Iowa 10 – Beresford, S.D., Orange CityRoad continues as Iowa 10 west (Avenue E north)
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ 2014 Volume of Traffic on the Primary Road System of Iowa (PDF) (Report). Iowa Department of Transportation. January 1, 2014. Retrieved July 17, 2015.
  2. ^ "Road Network (Portal)" (ESRI shapefile). Ames: Iowa Department of Transportation. April 9, 2021. Retrieved August 19, 2021.