A farm tractor.
Oh damn! Hadn’t even thought about that!
Ha, once in High School I got stuck behind one going about 10 MPH, on a road too narrow for passing (1 lane each direction with physical median). I was familiar with the area, so I turned off onto a side street, gunned it down a parallel street (probably too fast), and made it back onto the main road ahead of it.
Since one of you are probably familiar with Bend roads, it was on my way to Summit High (on lunch break, so I was probably in a hurry to get back to class), on Mt Washington Dr between Simpson and Skyliners. I used Flagline, Outlook Vista (a street that always made me think of Microsoft), and Hosmer Lake to pass the tractor.
I still have no idea what a vehicle like that was doing in that part of town, only time I've seen something like that in that area.