Desoto Ave between Blair Nebraska and Missiouri Valley Iowa. Take Desoto Ave South off Highway 30 (Lincoln Highway) all the way to I-29.
-- for those opposed to gravel/ loose rocks-- turn around at the end! Final 3.8 miles all gravel and loose rocks
Along this route you'll see the Missiouri River, Desoto Lake ( which is really a river connected from Missiouri River one point to another).You'll go through Desoto National Wildlife Refuge. In it there are parks, wildlife, bodies of water, nature in itself, very serene. I felt like I was alone in the world back before civilization. Don't go when dark, it would be spooky. Couple spots with about 50 ft of gravel, no big deal. At the end, after you get out of the park, you'll want to turn around for two reasons. 1- gravel will start and will last 3.8 miles and loose rocks will pick up. 2- not much scenery after exiting the park. I took the gravel route to see where it would lead, and it lead to a 15 minute at 15-20 mph annoying dirt/rocks ending at I-29. Other than the gravel, ride was very enjoyable, no traffic, no one on your rear end, no one distracting you, total serenity.
Road wasn't too bad to be honest. At the beginning, two spots approximately 50 ft of gravel. After leaving the park, lots of broken up road and the ending of 3.8 miles of gravel/loose rocks. Do the turn around when you see the "thank you for visiting" sign.
No shops, no civilized stops. However, there are a few parks, picnic areas, fishing spots, boating docks. Very peaceful amenities.
Motorcycle Road Additional info
I am a new rider and had little trouble with the dirt road. I went slow 15-20 mph