Wind RIver > Bighorn > Yellowstone. Not sure exactly but hundreds of miles. There is a dam or two. Also the Yellowstone has several sketchy diversion dams.
The whole Snake River from Teton NP down through Idaho, about 1000 miles. Again several dams but not so difficult to get around.
My good buddy did his masters thesis on land use in the Uinta Basin- for his research he put together a bunch of permits and I had the incredible opportunity to float from Steamboat Springs down to Powell. We ended up shuttling around Cross Mountain Canyon and putting in on the Little Snake above Yampa Canyon but otherwise it was contiguous (Yampa, Little Snake, Yampa, Green, Colorado). I forget exactly how many miles it ended up being but I think it was up in the 600s and all told it was an incredible 35 days on the river...
A forum community dedicated to whitewater kayaking, boating, and rafting enthusiasts. Come join the discussion about safety, routes, gear, models, styles, gear swaps, reviews, accessories, classifieds, and more!