Length in Iowa: 235 miles/378 kilometers
Northern terminus: Minnesota state line south of Elmore, MN
Southern terminus: Missouri state line south of Redding
Counties: Kossuth, Humboldt, Webster, Boone, Dallas, Madison,
Cities along route: Bancroft, Algona, Humboldt, Fort Dodge, Harcourt,
Boxholm, Ogden, Minburn, Adel, De Soto, Winterset, Lorimor, Afton, Arispe,
Mount Ayr, Redding
NHS: From US 18 in Algona to IA 141 in Dallas County
Freeway segments: None
Expressway segments: 6 miles, from IA 7 on the outskirts of Fort
Dodge to the US 20 interchange
6 miles with IA 9 in northern Kossuth County
4 miles with IA 175 in Webster County, north and east of Harcourt
4 miles with US 30 west of Ogden
5 miles with US 6, between Adel and I-80 at De Soto
2 miles with IA 92 west and north of Winterset
6 miles with US 34 east of Afton
2½ miles with IA 2 west of Mount Ayr
Designated: October 23, 1930, replacing IA 16 (I).
Paving history: At the time of designation, these segments were paved: IA 9 to Algona, the Humboldt/Webster county line to Fort Dodge, a point south of US 20 to IA 91 (now 175), the split with IA 17 (now 141) near Bouton to IA 7 (now 44) north of Adel, and from US 34 in Union County (including the multiplex) to the Union/Ringgold county line
1931: Paved from IA 7 to Adel and from Winterset to US 34
1932: Paved from IA 91 to US 30 (including the multiplex) at Ogden
1933: Paved from the city of Humboldt to the Humboldt/Webster county line and from US 20 to a point south of Fort Dodge (on a new diagonal alignment)
1935: Paved from Algona to the Kossuth/Humboldt county line
1936: Paved from the Kossuth/Humboldt county line to Humboldt and from the North River crossing in Madison County to Winterset
1938: Paved from the Union/Ringgold county line to Mount Ayr
1940: Paved from the Minnesota state line to IA 9 (on a new alignment, creating IA 91 (II) to serve Ledyard; the old alignment also followed what is now County Road P50 between Ledyard and IA 9). It was also paved from County Road G (now E57) south of Ogden to IA 141.
1947: Paved from De Soto to the North River crossing
1951: Paved from Adel to De Soto on a straightened alignment that included a new bridge across the Raccoon River. (The old alignment followed what is now 323rd Place and 330th Lane north of the river, and part of Overton Place south of the river. The old bridge was removed.)
1955: Last segment, from IA 2 west of Mount Ayr to the Missouri state line, paved
Major alignment changes:
November 18, 1960: Re-routed to the west of Fort Dodge (it had run into the city center); the old segment was redesignated as IA 413 and an extended IA 320.
1976: Re-routed to the west and north of Winterset along a new two-lane bypass.
The old route south of Winterset is now County Road P71.
November 19, 1990: Expressway segment between Webster County Road D20 and the relocated US 20 completed, connecting it with an existing segment between there and IA 7.
For alignment changes in Fort Dodge that are not listed here, see Jeff Morrison's Fort Dodge Highway Chronology page.