Interstate 35 (I-35) is a north–south Interstate Highway in the United States that runs from Laredo, Texas, to Duluth, Minnesota. In Iowa, the highway runs from south to north through the center of the state, roughly parallel to U.S. Highway 69 (US 69) and US 65. It enters the state near Lamoni from Missouri and continues north through the southern Iowa drift plain. In the Des Moines area, I-35 runs concurrently with I-80, and the two highways bypass Des Moines to the west and north. I-235, the only auxiliary route of I-35, serves the suburbs and downtown Des Moines; it begins and ends at the two interchanges where I-35 and I-80 meet. Near Mason City and Clear Lake, US 18 and Iowa Highway 27 (Iowa 27) overlap with I-35. 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. Construction of I-35 in Iowa took place over 17 years. The first section of the route that stretched from Cumming to Urbandale was opened on September 21, 1958. In the next 14 years, new sections of the route opened regularly, only leaving the section between Mason City and US 20 uncompleted. On November 14, 1975, the last section of the route was completed and connected the two noncontiguous sections of I-35. Route description Southern Iowa I-35 enters Iowa at the Missouri state line near the town of Lamoni. 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 until it again meets US 69 on the eastern edge of Lamoni. North of Lamoni is a rest area which overlooks the Grand River and provides pedestrian access to Decatur County's Slip Bluff County Park. North of the Grand River, the Interstate straightens to a north–south alignment. Near Decatur City, it intersects Iowa 2 at a diamond interchange. Continuing north, the Interstate slightly eases to the east. Two rural interchanges, for County Road J20 (CR J20) and CR H45/Elk Street, and another in Van Wert for CR J14/East Line Street dot the separating Decatur City and Osceola. The Osceola area is served by three interchanges for I-35. The first is a partial cloverleaf interchange with US 34. This junction is so configured because of US 34's proximity to the BNSF Railway