When I bought my P19, the seller was in oregon (where trailers are neither
licensed nor titled AFAIK), but he did have a colorado title for it (he had
moved out from there).
when I went to get it licensed in WA, they gave me all kinds of grief about
it, because they could not find a serial number on the trailer anywhere. I
still don't have clear title on it. I had to "apply for title" and I won't
actually be able to >get< a clear title until after 3 years (which i think
comes up late this summer). The state did rivet on an assigned number,
however.