Highway 2 was designated on November 3, 1941, to follow along the former IA Highway 3 through southern Iowa (designated on July 1, 1920 and decommissioned November 3, 1941). The former IA Highway 3 went from Nebraska City, Nebraska, to Fort Madison in eastern Iowa. In 1939, IA Highway 3 was paved from Benton to Mount Ayr, and from a point west of Kellerton to the Ringgold - Decatur County line. In 1940, the highway was paved from the Taylor - Ringgold County line to Benton. At the time of the decommission (November 3, 1941), the segments from Mount Ayr to west of Kellerton, and from the Ringgold - Decatur County line to Leon were gravel roads.

The the designation of Highway 2 on November 3, 1941, the road was paved from Decatur City to Leon, Decatur County. In 1942, the segments from Mount Ayr to west of Kellerton, and a county road (present-day R-18) south of Grand River to Decatur City in Decatur County was paved. The last segment from the Ringgold - Decatur County line was paved in 1946.

SOURCES:
http://iowahighways.home.mchsi.com/highways/iowa1-9.html#3a

Construction photographs courtesy of Kathy Gregg, August of 2009