The Simpsons has covered basically every holiday at this point, often many times over. They literally do a Halloween episode every season. Christmas has been covered on several occasions, including some really good episodes. You want an Easter episode? You got it! April Fool’s Day? They did a clip show built around it. The Simpsons also, naturally, has covered the Fourth of July. They only did it once, but it was a memorable episode worth shouting out for the holiday.
The episode is called “Summer of 4 Ft 2.” It is indeed a “Fourth of July” episode, but only sort of. It’s a Fourth of July episode like Die Hard is a Christmas movie. It’s true, but it’s not the most-important thing. The episode is really about Lisa, about summer, about childhood, and about Homer called Milhouse “Poindexter” a bunch of times.