The first section of I-80 to open for traffic, from the West Mixmaster to the Douglas Avenue interchange in Urbandale, opened on September 21, 1958. By the end of November 1959, the new interstate extended around the north side of Des Moines to US 69. Within a year, the East Mixmaster, where I-35 splits away to the north, was opened. By the end of 1960, from US 71 north of Atlantic to US 6 near Dexter, from I-35 to US 6 west of Newton, and from Iowa 38 near the Cedar River to US 61 in Davenport had opened to traffic.