Q: Where in the US is it legal to (1) buy and (2) use fireworks?

A: Fireworks laws are delegated by the Federal Gov’t to the states.  So, the answer varies by State with regards to consumer fireworks (classified as explosives 1.4g).  Different states have different regulations on when, what, and under  what conditions consumer fireworks may be sold and/or used.

An overview of the state by state laws can be found here:

In many states, such as Oklahoma, Texas, New Hampshire and California, the states have chosen to allow local municipalities (such as cities, townships or counties) to regulate fireworks.  So, there’s really not a short answer to “Are fireworks legal to buy/shoot where I live?” as its often up to the local jurisdiction.  

In most cases, the local fire marshal (basically, a fire police officer) is the one to ask.  Alternatively, you can visit the local offices for your municipality/local government entity and ask to see a copy of the ordinance/regulation for consumer fireworks.

Finally, display fireworks (classified as 1.3g and what you see at most professional shows) are both state and federally regulated.  They are subject to a different set of rules.  I presumed this question was regarding consumer fireworks only.

Michael Girdley