Originally Posted by
cheltzel
Was the entire trip SFO-UIN purchased as a trip with United? If so they will check your bags through to your destination. I have no idea about checking in/boarding passes with Cape Air. Someone who has done this at STL needs to jump in as I have no idea what the procedure is to go from UA to Cape Air at STL.
If your bags are checked all the way through at the start, they will transfer. Carry-on will be weighed and tagged when you check in @ Cape Air, and that is where you will get your BP. I have seen them bump people because the plane was too heavy.