Here is the list of species I saw during the trip, partially prepared using the new eBird Trip List functionality which is pretty snazzy. If you click on the link above it will take you right there, and you can browse each species, see locations, maps, dates, counts and so on (though I believe the Owls are suppressed) . It looks like this, a really cool feature.
I saw a total of 120 species, with the bulk of these in Colorado where the weather was warmer. As I moved north the diversity really thinned out. I only spent a few hours in Wyoming which explains why that is so small, and I drove through Nebraska in the dark! I had a day each in South Dakota and North Dakota, with more time in Minnesota, Wisconsin and Illinois. Here is the list broken out by State. I had in my mind a total of 100 species due to the paucity of birds in northern latitudes, I had not reckoned on the diversity present in Colorado. I saw almost everything I had targeted, the two rare Woodpeckers and the other two Rosy-finches will have to wait for another time. I am thinking that a few days in the Rockies as winter recedes in April could be the answer, but I need to research that - America is big place and there are still many States I have not visited.