My observations from last summers Northern Tier trip. I didn't leave until August 10th. So based on that information I would have passed most riders that left around the middle of June. I was traveling West to East. I rode everyday. Now we have to assume that some slipped past me while I was eating/checking things out. I imagine that number would be very small. I chatted with pretty much everyone that I passed except for a few. That being said I didn't pass more than 15 riders the whole way that had planned on the whole trip.
With the above being said..... I think more travel West to East so those riders I wouldn't have come into much contact with. That being said..... Common camping sites with guest books didn't have many names in them. I think routes like the Northern are much less traveled. Based on the guest books and the looks of the locals when they asked where I was from and where I was going..... Most just shook head in amazement.
So the number for the Northern Tier is much lower than I thought it would be based on my experience. I'm guessing that the number of tourists last summer on the Northern Tier who started and completed the whole thing would be less than 100.
Very loose use of any real statistics of course....
Lots of guessing in the above estimate. So take what my thinking is with a big grain of salt. Even if you look at Crazyguy you will not find a large number of Northern Tier journals. On the other hand you find way more Trans America route journals.
Wow..... don't know if anything I just wrote really means anything.... ymmv