One incident sticks out in my mind with windy's posts. I had impounded a couple Kymco ATV's in a rural area here, because the kids were riding on public roads, in traffic, no helmets, yada yada yada. The bikes came up clean, and were stuck into 30 day impound. The parents came and picked up the kids and the dad told me over and over about how he had just bought the bikes from Nevada, and never had registered them in CA (Yet. Of course). I told him he would need to show proof of ownership in order to get the bikes out of impound... All he had was a bill of sale. Come to find out, the bikes COULDN'T be registered in CA because he didn't have a title. The bikes sold at the next auction. California is one of the few states that require titles for damn near everything. Hell, bicycles valued over a certain dollar amount are issued titles now, because banks finance them.
As windy said, ANYTHING that is capable of being financed by a financial institution in the United States is able to get a title. Just because your particular state doesn't require a title for registration reasons, does not mean that you cannot get a title for the bike. A certificate of origin, as windy stated, is what you submit to your governing agency to obtain the title. EVERY state will issue a title if it came with a certificate of origin. That is the whole purpose of the COO.
I bet the banks that lent you the money on the bike that you purchased didn't just HOPE that you were going to return the bike if you stopped making payments... No siree bob, they had a title (perhaps paperless), but they had a title to that bike in the event that you defaulted, and they needed to repo the bike. I'd be willing to bet a good chunk of the bikes out there without titles have never been paid off, but the bank decided to eat the loss, rather than pursue reposession.