This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
Several states still require some type of permit to fly model rockets.
The requirements vary greatly between the states. Also, local
municipalities are free to impose additional restrictions beyond those
defined in NFPA 1122 and any state laws. Check with your local fire
marshal for restrictions in your area. For example, the states
of Rhode Island, and California have stricter regulations than NFPA 1122.