Iowa Highways: 420 to 478

Jump directly to route:
400-419 420 421 422 424 426 428 431 432 434 437 The 900 Series
438 450 460 461 463 470 471 475 478  
For an explanation of the route listings, click here.

Iowa 420
Designated: December 14, 1960
Decommissioned: 1968
Original northwestern terminus: IA 136 in Dyersville
Original southeastern terminus: US 20 southwest of Dyersville
Counties: Dubuque
Paving history: The entire road was paved at the time of designation.
Replaced by: Unsigned IA 968 before November 29, 1989; now local roads (2nd Avenue SE in Dyersville and Olde Hawkeye Road). This was also a former segment of US 20 that carried the IA 416 designation for a year after US 20 was relocated.
Iowa 421
Designated: 2000
Decommissioned: February 18, 2003
This unsigned highway was originally designated to two former segments of US 61 northeast of Muscatine in Muscatine County, totaling 0.7 miles, that were displaced by the opening of a nearby four-lane segment in 2000. A map showing the original two segments can be found on Jeff Morrison's Super Secret Route Page and in the legal description. In 2001 a third segment (roughly two miles) between Zachary Avenue in eastern Muscatine County and the east end of the Blue Grass bypass in Scott County was added to the mileage of IA 421 upon the opening of the bypass. Scott County and the city of Blue Grass took over their segments of IA 421 on May 12, 2003, and Muscatine County followed suit on June 6, 2003.
Iowa 422
Designated: August 11, 1964
Decommissioned: March 9, 1976
Original northern terminus: US 169 in central Kossuth County
Original southern terminus: Burt
Counties: Kossuth
Paving history: The entire road was paved at the time of designation.
Replaced by: Unsigned IA 969; Kossuth County took over jurisdiction on July 1, 1980, and it is now 300th Street. It was created after a minor shift in US 169's alignment moved the road away from Burt.
Note: The Highway Commission originally assigned the IA 422 number to a former US 18 segment in Rudd that was bypassed in 1959, but the designation was scratched from the Commission's meeting minutes from December 12, 1960.
Iowa 424 (I)
Designated: November 1961 (number assigned December 14, 1960)
Decommissioned: July 1, 1980
Original southwestern terminus: (former) IA 111 in Britt; it was truncated west of Britt's east city limits in 1969
Original northeastern terminus: US 18 east of Britt
Counties: Hancock
Paving history: The entire road was paved at the time of designation.
Replaced by: City streets; this route replaced a two-mile segment of US 18. IA 424 disappeared from state highway maps after 1969 so it is unknown if the 0.44-mile segment outside of Britt was signed after that given its short length.
Iowa 424 (II)
Designated: 1999
Decommissioned: July 1, 2003
Northern terminus: US 218/IA 27 north of Olds
Southern terminus: US 218/IA 27 south of Swedesburg (with a 1½-mile break along the segment that is still part of IA 78, which was not moved when US 218 was)
Counties: Henry
Paving history: The entire road was paved at the time of designation.
Replaced by: County Road W60 (although it may not be signed as such; the E-911 name is James Avenue)
Terminus photos
This unposted road was a former segment of US 218 that was superseded by a four-lane Avenue of the Saints segment.
Iowa 426
Designated: December 14, 1960
Decommissioned: July 14, 1980
Original western terminus: IA 92
Original eastern terminus: Rose Hill
Counties: Mahaska
Paving history: The entire road was paved at the time of designation.
Replaced by: Local road in Rose Hill; the segment between IA 92 and the west city limits was eventually removed. The segment in Rose Hill remained under state control until April 6, 1981. IA 426 was a replacement for a dislocated segment of IA 92 that was bypassed three months prior to the designation.
Iowa 428 (I)
Designated: November 1965 (number assigned November 4, 1964)
Decommissioned: July 1, 1980
Original western terminus: Anamosa
Original eastern terminus: The junction of US 151 and IA 64 east of Anamosa
Counties: Jones
Paving history: The entire road was paved at the time of designation.
Replaced by: County Road E28; it was a former segment of IA 64 which was truncated after US 151 was re-routed around Anamosa.
Iowa 428 (II)
Designated: October 1, 1980
Decommissioned: July 1, 2003
Original northwestern terminus: Maquoketa Caves State Park
Original southeastern terminus: US 61 north of Maquoketa
Counties: Jackson
Paving history: The entire road was paved at the time of designation.
Replaced by: County Road Y31, plus a short unnumbered spur road leading into Maquoketa Caves State Park. Before 1964 this was IA 130 (III).
Terminus photos
Iowa 431 (I)
Designated: December 2, 1998
Decommissioned: February 1, 2001
Original northern terminus: US 218/IA 27 northwest of Waverly
Original southern terminus: IA 3 in Waverly
Counties: Bremer
Paving history: The entire road was paved at the time of designation.
This unsigned number was designated to a 1.9-mile segment of US 218 after the bypass was completed; it was, and still is, signed as part of Business US 218.
Iowa 431 (II)
This designation was given to the former segment of US 30 through Le Grand in Marshall County that was bypassed in late 2004. The segment through Le Grand was turned over on October 24, 2005, after rehabilitation work was completed, but the Iowa DOT's map of Marshall County showed it as a state highway until 2014. IA 431 existed in two segments, as the former US 30 bridge over the Union Pacific railroad tracks has been removed.
Iowa 432 (I)
There is a legal description for an IA 432 in Hamilton County that was approved by the Highway Commission on September 4, 1966, but rescinded on November 23, 1966, without any documented reason. Based on the route description, it may have been intended to replace US 20 and IA 17 through Webster City once the then-proposed US 20 freeway opened. Since US 20 would not bypass Webster City until 1979, this IA 432 never came to pass, and the segments in question ultimately ended up under local control.
Iowa 432 (II)
Designated: June 24, 1998
Decommissioned: May 1, 2003
Original northern terminus: IA 163
Original southern terminus: IA 92 in Oskaloosa
Counties: Mahaska
Paving history: The entire road was paved at the time of designation.
This was used for an unposted former segment of IA 163 that was displaced when the bypass of Oskaloosa opened; it was the first bypassed highway to carry a "secret" number outside of the 900 series. State highway maps from 2001 to 2003 showed it, but the highway was never signed when it was active. However, the city of Oskaloosa still refers to it as "Highway 432", as an "IA HWY 432" sign can be found at the roundabout junction with Pella Avenue.
Former terminus photos
Iowa 434
This designation was given to the former segment of US 34 from Danville through Middletown to West Burlington that was bypassed when a new four-lane segment opened in November 2005. The cities of Middletown and West Burlington accepted jurisdiction of their pieces of the road on August 1, 2007; Des Moines County accepted jurisdiction of its segments on October 1, 2007; and the city of Danville accepted jurisdiction of the last segment on May 8, 2008.
Iowa 437
This was a former segment of IA 137 in Eddyville in Wapello County that was abandoned when IA 137 was realigned to connect with the US 63 bypass in 2005. It was turned over to the city of Eddyville on March 23, 2009. The road, which dead-ends in both directions, has no name.
Iowa 438
This number was originally given to an unsigned bypassed segment of US 218 (Grand Avenue in Mount Pleasant) in Henry County, dating back from the opening of the Avenue of the Saints bypass in December 2001. It originally ran southward from US 34 (Washington Street), dead-ending south of 255th Street; the segment north of there still carried southbound US 218 traffic. In March 2002, after US 218 was fully re-routed onto the bypass, the IA 438 designation was extended northward to the interchange with US 218/IA 27 north of Mount Pleasant. The segment south of Washington Street was turned over to local control on September 23, 2003, and the city took over the segment between the US 218/future US 34 interchange and Washington Street on October 1, 2004 (that segment is still part of Business US 218). The only remaining segment with the IA 438 designation is a short piece between the US 218/IA 27 exit ramps and the interchange with the US 34/IA 163 bypass.
(A side note: The unsigned road that exited from northbound US 218/IA 27 at the north bypass interchange and ended at IA 438 was designated as IA 534 until the rest of the US 34 north bypass was completed in 2005.)
Terminus photos
Iowa 450
This is an unsigned, 0.28-mile connecting highway between IA 10 and the interchange with IA 60 in Sioux County north of Alton, following 450th Street (hence the number), that the state took over as of January 31, 2005. This highway does not appear on any maps, but it was listed on the Wisconsin DOT's 2008 Numbering State Trunk Highways document. (Terminus photos)
Iowa 460
This unsigned highway was assigned to two former segments of US 218 and IA 394, totaling about 5½ miles, after the bypasses of Donnellson and Argyle in Lee County opened in 2004. One segment ran from County Road J56 through Donnellson to County Road J62, while the other ran through Argyle. After additional four-lane segments of the Avenue of the Saints opened, a small piece of old US 218 near 155th Street and the bypassed IA 394 segment from Belfast Road to the old Des Moines River bridge at the Missouri state line were added to IA 460's mileage. All segments were transferred to local control on August 8, 2007, and are known as 180th Avenue in Lee County.
Iowa 461
Length: 11 miles/18 kilometers
Northern terminus: I-80 exit #295 in Davenport
Southern terminus: I-280 exit #6 in Davenport

Counties: Scott
Paving history: The entire road was paved at the time of designation.

This is the official designation of Business US 61 in Davenport, which was created when US 61 was rerouted onto I-80 and I-280 in September 2011. From I-80, the route follows Brady Street, the one-way pair of Welcome Way/Harrison Street (southbound) and Brady Street (northbound), and River Drive. The segment along River Drive, which includes a short multiplex with US 67, follows the Great River Road east of IA 22.
Note: While the IA 461 designation was approved by the DOT on May 28, 2010, per the legal description, signs along US 61 itself were not changed until September 2011.
Terminus photos
Iowa 463
This designation was given to a former segment of US 63 in Bremer County northwest of Frederika that was bypassed by a new four-lane segment in late 2009. It was turned over to Bremer County by the end of 2010, after the road was resurfaced.
Iowa 470
This 0.6-mile unsigned highway follows 3rd Street and Main Street in Merrill, Plymouth County. While this was part of US 75 before 1957, it is unknown when this segment was added back to the state highway system as it has only appeared on city and county maps since the early 2010s.
Iowa 471
Length: 11 miles/18 kilometers
Northwestern terminus: US 20 (exit #71) and US 71 north of Early
Southeastern terminus: IA 175 between Odebolt and Lake View

Counties: Sac
Cities along route: Early
Designated: June 14, 2016, along a former segment of US 71 after the latter was rerouted along the former IA 196.
Paving history: The entire road was paved at the time of designation.
Iowa 475
After US 75 was routed onto I-29 in late 1968, this designation was given to 32 miles of old US 75 between Sioux City and Onawa in Monona and Woodbury counties. It did not appear on any official state highway maps, but the Iowa Primary Road Sufficiency Logs and Rand McNally maps from this era both showed this route. On March 9, 1976, it became the unsigned IA 970. Monona County's segments were turned over in 1980 (Onawa accepted its segment on August 19, Whiting on August 22, and the county on December 19). Sergeant Bluff followed suit on July 1, 1980, and Salix and Sloan did the same on July 1, 1981. That same day, Sioux City took over its share of the road from Donner Avenue to the south city limits; Sioux City later took over the rest of its share except for a small segment of less than 200 feet south of Singing Hills Boulevard on December 23, 1994. The rest of Woodbury County's share was decommissioned on December 27, 1996, and the last segment in Sioux City was given to the city on July 1, 2003. The entire route is now County Road K45.
Iowa 478
This was a former segment of US 63 between the north city limits of New Hampton and IA 24 in Chickasaw County that was bypassed in 2002 after the bypass of New Hampton opened; it is signed as part of Business US 63. It was transferred to the city on November 1, 2003. (Per correspondence between Dennis Swanson and the Iowa DOT, the transfer was delayed until the railroad crossing to the Sparboe Foods plant was repaired.)

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