16 and 1/2 hours
9 hours
23 and 1/2 hours
4 hours
A little under three hours
21 hours
just under 10 hours
23 and 1/2 hours
12 and 1/2 hours
12 and 1/2 hours
MapQuest says about 23 hours.
It all depends on where you are going to in Iowa. You can go southeast on Highway 42 (Arrowhead Parkway) from Sioux Falls and reach the Iowa border in about 20 minutes.
It is an estimated 25 hour drive covering 1,485 miles.