This is an annual cross-state ride called RAGBRAI. It's been going for 52 years now. Riders typically use support teams, but I ride self-supported from the center of the state, ride half the route, and ride home. More photos:
That's why I do it the way I do it; I only did like a day and a half on route this year, and the rest of the time I'm either riding out, riding back home, or just fucking around in a state park somewhere for a day or two. The bags are heavy but they have their advantages.