Just so everyone is aware of what the rules are when registering your boat here is an excerpt from the USCG Office of Boating Safety:
Federal Requirements and Safety Tips for Recreational Boats
Registration, Numbering, and Documentation
All undocumented vessels equipped with propulsion machinery must be registered in the state of principal use. A certificate of number will be issued upon registering the vessel. These numbers must be displayed on your vessel. The owner/operator of a vessel must carry a valid certificate of number whenever the vessel is in use. When moved to a new state of principal use, the certificate is valid for 60 days. Check with your state boating authority for registration requirements. Some states require all vessels (including documented) to be registered.
Some larger recreational vessels may be documented. The certificate of documentation MUST be on board a documented vessel at all times. A document serves as a certificate of nationality and an authorization for a specific trade. A documented vessel is not exempt from applicable state or federal taxes, nor is its operator exempt from compliance with federal or state equipment carriage requirements. A documented vessel may also be required to pay a registration fee and display a validation sticker in some states.
So be aware that if you do register the boat outside of the state of principal use, and the USCG decides to check you out, you may be fined.
If your interested in your State Boating Laws and Statistics take a look at the PDF file I've attached.