It enters the state near Lamoni from Missouri and continues north through the southern Iowa drift plain.

I-235, the only auxiliary route of I-35 in the state, serves the suburbs and downtown Des Moines; it begins and ends at the two interchanges where I-35 and I-80 meet.

Shortly after, US 18 splits off to the west in Clear Lake, while Iowa 27 runs with I-35 until they reach the Minnesota state line.

The first 10-mile-long (16 km) section of the route that stretched from Cumming to Urbandale was opened on September 21, 1958.

An interchange that provides access to the adjacent US 69 and East 100th Street is situated over the state border.

The highway travels to the north-northeast for four miles (6.4 km) until it again meets US 69 on the eastern edge of Lamoni.

This junction is so configured because of US 34's proximity to the BNSF Railway line, which carries Amtrak's California Zephyr.

Northwest of Osceola is the western end of Iowa 152, which connects I-35 and US 69 at a narrow point between the two routes.

Common among all of the rest stops are separate men's and women's restrooms, payphones with TDD capabilities, weather reporting kiosks, vending machines, and free wireless Internet.

Story County is the home of Iowa DOT and the location where the historic Lincoln Highway and I-35 intersect.

[10] Jefferson Lines provides intercity bus service along the length of I-35 in Iowa serving seven communities along the route.

The Des Moines Bus Station serves as a major transfer point along the I-35 route.

Within five years, the Interstate had grown to 55 miles (89 km), extending from US 34 in Osceola to the eastern interchange with I-80 and I-235.