When it was extended into the state in 1929 , it only traveled 6 miles ( 9.7 km ) in Sioux City before crossing the Big Sioux River into South Dakota .
US 77 has never been a long route in Iowa .
When US was extended into the state in 1929 , US only traveled 6 miles ( 9.7 km ) in Sioux City before crossing the Big Sioux River into South Dakota .
US 77 has never been a long route in Iowa .