Yeah, every state is different, which might pose a problem if traveling by Rebel. In AZ, it's based on engine size, it must be at least 150cc. There is no way I would ride a 150cc bike on a freeway. I do ride the Rebel on the freeway quite often, in the right lane, at an indicated 65 mph. I have stock gearing, and won't push it any harder. The Rebel is about the minimum size/powered bike I would ride on the freeway, and by that I mean the interstate. It would be suicide to try and ride a Rebel on the local urban freeways, which have a lot more lanes, a lot more exits, a lot more traffic, and much higher speeds.
One neat thing about AZ is that it has no minimum speed limit. You can go 40 mph if you want to, legally anyway, though hardly safely. AZ also has a "slow moving vehicle" law, if your vehicle has flashing lights and an orange triangle visible from the rear, it can go as slow as you want. That will work on a large truck, but I wouldn't try it on a bike. Back when I used to ride mopeds, which definitely weren't freeway legal, with 50cc, and a top speed of 30 mph, I would always ride on the shoulder of non freeway roads, where speed limits were still 55-65 mph, and cars often went much faster. But I also passed a lot of bicycles also riding on the shoulders of these roads. I figured if it was reasonably safe for a bicycle, it was for a moped as well. Some people thought I was crazy, but many people have crossed the country on bicycles, mopeds, and 50cc scooters, and it has proven to be fairly safe. Jerry.