Length in Iowa: 152 miles/245 kilometers
Northern terminus: South Dakota state line
(Big Sioux River) at Sioux City
Southern terminus: Missouri
state line near Hamburg
Counties: Woodbury, Monona, Harrison, Pottawattamie, Mills,
Cities along route: Sioux City, Sergeant Bluff, Salix, Sloan,
Whiting, Onawa, Blencoe, Little Sioux, Mondamin, Missouri Valley, Crescent,
Council Bluffs, Pacific Junction, Hamburg
From the Missouri state line to Exit #71 (I-680)
From Exit #71 to the South Dakota state line
9½ miles with I-680, from Exit
#61 to Exit #72 in Pottawattamie County
5 miles with US 6, between Exit #53A and Exit #48; this includes a 2½-mile triplex with I-80 from Exit #51 to Exit #48 in Council Bluffs (exit numbering follows I-80 here)
12 miles with US 275, from Exit #47 in Council Bluffs to Exit
#35 in Mills County
October 1, 1958: Segment from IA 12 to Gordon Drive (then US 20) in Sioux City opened. This incorporated an upgraded US 77 segment between Hamilton Boulevard and Gordon Drive, including an interchange with the US 20/77 Combination Bridge, that opened on December 15, 1957, but this segment may not have been signed as I-29 right away.
November 26, 1958: Segment from US 30 near Missouri Valley to the US 75 (16th Street, now IA 192) exit in Council Bluffs opened.
November 28, 1959: Segment from the industrial area exit (now Singing Hills Boulevard)
in Sioux City to IA 140 (now 141) near Sloan opened
July 15, 1960: Segment from Gordon Drive in Sioux City to the Sioux City industrial area opened
October 26, 1961: Segment from IA 141 to IA 175 opened
December 15, 1961: Bridge from Sioux City into South Dakota opened. (The bridge was built in 1958 but wasn't opened until South Dakota opened its stretch of I-29 south of Junction City.) The northbound span of the bridge collapsed on April 1, 1962, as a result of Big Sioux River flooding; traffic was briefly re-routed onto the old US 77 and US 20 bridges until the bridge reopened.
December 7, 1967: Segment from IA 175 to US 30 opened
October 25, 1968: Segment from 16th Street (former US 75) to 9th Avenue in Council Bluffs opened
December 22, 1969: Segment from IA 192 (west of the I-80 split) in Council Bluffs to IA 370 opened
November 1, 1970: Segment from the western split with I-80 to IA 192 (duplex with I-80) opened
December 4, 1970: Segment from IA 370 to US 34 near Glenwood opened
November 10, 1971: Segment between 9th Avenue and I-80 in Council Bluffs opened
December 10, 1971: Segment between US 34 and County Road J18 (now J24 after a stint as IA 145) opened
December 1, 1972: Segment between J18 (now J24) and IA 2 opened
December 15, 1972: Segment between IA 2 and County Road J64 (now IA 333) at Hamburg opened
August 31, 1973: Last segment, from J64 (now IA 333) into Missouri, opened
I-29 generally follows the route of old US 75 between Sioux City and Council Bluffs in the Missouri River floodplain — in fact, the two routes
were duplexed between 1969 and 1984, before US 75 was re-routed into Nebraska.
The latest state transportation plan includes money for improving I-29 in Council Bluffs and Sioux City. The segment through Council Bluffs will involve construction of a "dual, divided freeway" for the I-29/80 multiplex (detailed here) with three local lanes and three express lanes in each direction. Information on the Council Bluffs reconstruction is here, while information on the Sioux City reconstruction is here.
All of I-29 is part of the Lewis and Clark Trail.
Length in Iowa: One-quarter of a mile/0.4 kilometer
Western terminus: Nebraska state line (Missouri River);
it continues for three more miles westward into Nebraska before ending at US 77 in South Sioux City
Eastern terminus: I-29 in Sioux City; the freeway continues eastward from I-29 as US 20.
Exit lists: Entire route
Multiplexes: With US 20 and US 75
for its entire route.
History and Notes
One of the 1968 additions to the Interstate system, I-129 was finished on November 22, 1976. (The I-129 number was approved by AASHTO on June 23, 1969.) Starting in 1997 there was some speculation that I-129 had been decommissioned, since Kurumi's page originally noted that
the I-129 signs at the junction with I-29 were no longer there. However, some
misc.transport.road readers reported in July and August of 1998 that I-129 was
spelled out in text (instead of being depicted with an I-129 shield) on those signs.
There are a few examples of this on the Sioux City page in the Photo Gallery. According to an AARoads blog entry from May 2, 2007, the DOT made the change because drivers were confusing I-129 with I-29, and the text I-129 was intended to make the highway stand out differently from I-29. In 2004, some of the signs on southbound I-29 were replaced with new signs with I-129 shields, and new signs with I-129 shields were put up on northbound I-29 in late 2013 as part of the ongoing reconstruction of I-29.
Reports on misc.transport.road in mid-2000 stated that the existing US 20 freeway
and the new US 75 bypass would become an extension of I-129 upon its November 2001 opening,
but there is currently no I-129 signage despite the addition of exit numbers on the US 20 freeway in mid-2001. (The exit numbering created two Exits 1 for US 20 travelers — at I-29 and at Lakeport Street — in addition to the Exit 1 at US 77 in Nebraska.) But long-range plans from that time called for a 28-mile loop (possibly designated I-429) around Sioux City which would have involved US 20/75 and a north bypass to connect with I-29 near North Sioux City, South Dakota. It was mentioned in a July 26, 2000 article in the Sioux City Journal, but there does not appear to be any support for the road in South Dakota at the present time, nor does it appear in Iowa's current transportation plan.