Actually they are illegal in some towns in many states. Do a google search and you will see a whole bunch of them. I couldn't find any in NH though.
In Cambridge, MA, you can only use it during certain times of the year during specific hours. It is banned on Sundays and holidays.
http://www.cambridgema.gov/theworks/...afblowing.aspx
In Arlington, MA, you can't use them between May 15 and Oct 15.
http://arlington.patch.com/groups/po...ith-compromise