Iowa 78 heads east, serving the communities of Pekin, Ollie, and Richland.

East of Richland, it intersects Iowa 1; the two routes cross into Washington County, running together for 7 miles (11 km).

78 was created in the 1920s as a 5-mile-long (8.0 km) spur route which connected Winfield to Primary Road No.

The original section from Olds to just south of Winfield was the only fully paved road at the time.

After the expressway opened in 1999, US 218 was placed onto the new road while Iowa 78 stayed on the old two-lane alignment.