Between 1930 and 1968, the highway now known as Iowa 182 was called
Iowa 26. This was the second instance of Iowa 26. The first was designated in 1920 with the rest of the primary highway system. It was originally a
spur route from Primary Road No. 19 (now US 18) to
Rock Valley. Iowa 26 was extended north from Rock Valley back to US 18 in 1929. In 1930, US 18 was rerouted in
Lyon and
Sioux counties. The new routing of US 18 went through Rock Valley, thus eliminating the need for Iowa 26, which had connected Rock Valley to US 18. The Iowa 26 designation was moved northwest. It replaced County Road S, which followed the same course Iowa 182 now follows. On January 1, 1969, the
Iowa State Highway Commission, now known as the Iowa Department of Transportation,
renumbered several
state highways. The changes to the highway system fixed a number of issues: creating continuous route numbers across state lines, removing duplicate route numbers where they were unnecessary, and extending route numbers in some locations. In this case, the former Iowa 182 in
Allamakee County crossed into Minnesota and became
Trunk Highway 26. The two routes' numbers were switched and have remained the same since then. ==Major intersections==