Depends on the state. In our state, if you are commercial (and that includes cowboys going to rodeo where a prize can be won), if the trailer is over 10K you need a CDL, even if you are pulling it with a bicycle. Ag exemptions typically exempt the first 150 air (nautical) miles from home.
If commercial and crossing state line, and over 10K CGVW, you need a DOT#, medical card, log books, and all that jazz.
