Sioux City, IA to near Mankato, MN
Rationale: Although a pair of state routes, the IA 60/MN 60 corridor is a major inter-city corridor within Iowa and Minnesota. Along with US 169, it serves as a shortcut from the Twin Cities to I-29 and points southwest, and is a designated NHS corridor. Given that US 77 currently ends in Sioux City, the IA 60/MN 60 corridor makes for a logical extension. US 77 would duplex with US 75 up to Le Mars, IA, and then would take over the IA 60/MN 60 corridor up to US 169, where it would then terminate.
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