which is probably why the person you're replying to didn't say "July 4th only occurs in the US of A" but instead said "July 4th is only celebrated in the US of A"
You'd be hard-pressed to find it occuring in Iran.
Do they just skip from the 3rd to the 5th in Iran and have some kind of un-leap year? This is news to me. I thought the calendar was the same all over the world.
Jokes aside, the calendar is in no way the same all over the world.