Length in Iowa: 80 miles/128 kilometers
Northern terminus: Minnesota state line
north of Rock Rapids
Southern terminus: Nebraska state line (Missouri River)
at Sioux City with I-129 and US 20.
Counties: Lyon, Sioux, Plymouth, Woodbury
Cities along route: Rock Rapids, Sioux Center, Maurice, Le Mars,
Merrill, Hinton, Sioux City
NHS: From IA 60 north of Le Mars to the Nebraska state line
11 miles, bypass to the south and east of Sioux City.
4 miles, bypass to the west and north of Le Mars. This connects with the IA 60 expressway that extends northward into Minnesota.
Expressway segments: 16 miles, from the end of the freeway segment at Sioux City
to Le Mars. (The segments through Merrill and Hinton are four-lane undivided highways where the speed limits are reduced to 35 miles per hour.)
Exit lists: From I-29 in Sioux City to Le Mars
1 mile with IA 9 through Rock Rapids
1 mile with US 18 in northern Sioux County, north of Perkins
4½ miles with US 20, from the Gordon Drive interchange
east of Sioux City to the Nebraska state line; this includes a quarter-mile with
I-129 between I-29 and the state line.
Designated: October 16, 1926, to the former IA 22 (I) (north
of Le Mars), IA 5 (I) (between Le Mars and Sioux City), part of IA 12 (between Sioux City and Missouri Valley), and part of IA 6 (I) (between Missouri Valley and Council Bluffs, sharing US 30 until December 1931).
Paving history: At the time of designation, the segment from Le Mars to Whiting was paved.
1926: Paved from Whiting to Onawa by the end of the year
1927: Paved from Missouri Valley to Council Bluffs
1928: Paved from the Sioux/Plymouth county line to Le Mars
1929: Paved from Onawa to Missouri Valley
1934: Paved from Rock Rapids to the junction with IA 27 (III) east of Alvord and from Sioux Center to the Sioux/Plymouth county line
1935: Paved from the junction with IA 167 east of Doon to the Lyon/Sioux county line
1936: Paved from the Minnesota state line to Rock Rapids and from IA 27 to IA 167
1938: Last segment, from the Lyon/Sioux county line to Sioux Center, paved
Major alignment changes:
April 1930 (approved March 19): Straightened from Rock Rapids southward to US 18 before paving, creating
IA 167 to serve Doon; the previous alignment
south of Doon followed present-day County Road K45.
July 23, 1934: Re-routed from its former alignment along Fairmount Street, Leech Avenue, Rustin Street, Jay Avenue, Morningside Avenue, and Lakeport Street south of US 20 in Sioux City to a new western alignment that eventually became Lewis Boulevard. The segment along Lakeport Street became IA 230 (II); the rest became
IA 141, which had multiplexed with US 75 up to this point.
November 26, 1958: Rerouted onto US 30 and the newly-opened I-29 between Missouri Valley and Council Bluffs. The road that it followed into US 6 at Council Bluffs (16th Street) is now part of IA 192. The old route, which it had shared with US 30A, later became part of IA 183 and is now County Road L20.
October 21, 1966: Duplexed with I-480/US 6 from Council Bluffs into Nebraska
October 25, 1968: Duplexed with I-29 between Sioux City and Missouri Valley and from 16th Street to I-480 in Council Bluffs. Its old segment between Sioux City and Mondamin is now County Road K45, after portions were designated as unsigned IA 475, later IA 970 (Sioux City to Onawa), and IA 986 (Harrison County north of IA 301) until the 1980s. IA 127 and IA 183 replaced the old US 75 segment between Mondamin and Missouri Valley, and the old segment along 16th Street in Council Bluffs was designated as unsigned IA 973 until the city took control on September 15, 1971; that segment later became part of IA 192.
December 6, 1984: Re-routed along the former US 73 in Nebraska, eliminating most of the duplex with I-29 and removing the segments through Monona, Harrison, and Pottawattamie counties. AASHTO approved the relocation on May 23, 1984. (After the Sioux City freeway bypass opened in November 2001, US 75 was taken off I-29 entirely.)
For street alignments in Council Bluffs, see Jeff Morrison's Council Bluffs/Omaha Highway Chronology page.
For street alignments in Sioux City, see Jeff Morrison's Sioux City Highway Chronology page.
November 10, 1949: Expressway segment between Merrill and Hinton opens (this is Iowa's oldest four-lane divided highway that is currently in use)
December 8, 1949: Expressway segment between Hinton and the Plymouth/Woodbury county line opens
June 25, 1957: Expressway segment between Le Mars and Merrill opens
November 19, 2001: 7-mile freeway segment from the northeast edge
of Sioux City and Gordon Drive opened; US 75 was then completely taken
off I-29 and partnered with US 20 along the existing freeway segment.
November 7, 2006: 2-mile segment of the Le Mars bypass opens between IA 3 and the existing US 75. Traffic temporarily followed IA 3 into Le Mars.
November 22, 2006: 2-mile segment between IA 3 and IA 60 opens, completing the Le Mars bypass, which was delayed from its original 2002 completion date as a result of an alignment change. (A segment between Merrill and the south end of the bypass was still open to two lanes until June 21, 2007.)