Holy macaroni, you used Google with the bicycle feature to map your route. DON'T DO THIS! At least in Iowa you'll end up riding on gravel roads. Also you selected some high traffic roads that I wouldn't take. But some people just don't care. Use the map at http://www.iowadotmaps.com/msp/pdf/bikemap.pdf and try to avoid the red roads. That's at least my philosophy. A printed version of the map can be gotten from most bike shops in Iowa.

Specifics:

* US Hwy 52 to Dubuque. I don't see a simple solution to avoid this road without changing your route significantly.

* Hwy 150 to West Union. If you want ot go through West Union take W51 north from Arlington to Elgin and then east on B64. Otherwise go from Arlington to Maynard and take W25 north through Donnan and Hawkeye before joining US Hwy 18.

* US Hwy 218 / Hwy 27 between Nashua and Rudd. There are plenty of options there to avoid this stretch, depending if you want to go through Charles City and/or Mason City.

* US Hwy 65 out of Mason City. Use instead B20 going west, on the north side of Clear lake. Then take B14 to Forest City, A42 through Bancroft and Ringstead. Take then A34 all the way to the Nebraska border (you need to drop down to A48 briefly before the Okoboji lakes area)

* After you cross US Hwy 169 you route uses gravel roads. Not many sane tourers would use these. The bullet above has a alternate route but there are many other great possibilities. Just use the map mentioned earlier. Also note that this area you might not pass a gas station or convenience store for a long time. So plan accordingly.