Dating back to 1910, the route US 6 follows was originally the Great White Way and River-to-River Road. Both were auto trails which connected Council Bluffs and Davenport. When the U.S. Highway System was created in 1926, the highway was designated U.S. Highway 32. US 32 was renumbered in 1931 as US 6 was extended to the west coast. As the Interstate Highway System expanded in the 1950–1970s, US 6's importance as a cross-state route was diminished by I-80. As a result, the least-traveled sections of the route were moved onto I-80 and control of the vacated sections of highway was given to local jurisdictions.