It's a toss up for me......
1966-Provo, Utah. Family Vacation. The most amazing 4th celebration/aireal display I've ever seen to date.
Then a few years later, as a teen, one of the local 4th 'traditions' was to have bottle rocket wars in a field appx 60-70 cleared acres on both sides of a rural road just outside of city limits. Three guys in the back of my buddy's old early 60's Datsun p/u and two in the front. The guy in shotgun, helped navigate and managed the ammo. Us guys in the back were 'gunners'. I dont have to tell you what happens when an enemy round hits your 12 gross ammo dump in the front floorboard! The truck burned to the ground. No one ever got hurt, but I guess it was the last straw. The nearest city annexed that stretch of road by the next summer, and the 'tradition' was no more.