The first segment of interstate highway to open in Iowa was not signed as an interstate highway.
Recent research from Jason Hancock has revealed that when the Combination Bridge interchange in Sioux City opened at the end of 1957, there were no I-29 shields, just US 20 and US 77. The new pavement went west to Hamilton Boulevard (which, at the time, was an extension of Isabella Street), where it stopped for about 10 months until the entire riverfront four-lane to IA 12 opened.
That means the concrete from the Hamilton Boulevard area that started to be removed last month (see the KMEG story embedded above) is more than 60 years old. I’m surprised it remained there all this time, but then, other locations in Iowa have much older concrete on lesser-traveled roads.