This is still a thing, at least if the number of fireworks stores right at state lines are any indication. (I recently saw some along the Georgia-Tennessee border, although I can't remember which side they were on.)

It is even stranger in Texas, where the state says they are OK to sell at certain times of year but most large cities and towns prohibit them. Thus, you see seasonal roadside stands set up in unincorporated areas.

Tennessee - the restrictions are very loose there.