Every single April 19th I would manage to forget to get up and be there at 6am for the re-enactment (friends would tell me, ya ain't missing a lot).
Every employer I had there would always give us the day off, and the Boston Marathon would be playing on any TV in the area stores and bars.
To me, this was OUR holiday, just as Texas celebrates their own Texas Independence Day, Hawaii has King Kamehameha Day, Louisiana (and Alabama) have Mardi Gras (as an actual state holiday).
I thought of it is history and culture.
Part of the thing that makes me love this country so much is something I didn't always see elsewhere nor do I read about - other nations, parts of nations - they self-identify because of blood. Genes. Ethnicity, race and so on. Some countries have many such parts of their country where they speak their own language, have a distinctive culture and history. But it's genes.
You can live in France, have children in France and learn the language and culture. Ditto Japan, China, Spain, Turkey and so on. But you'll never be French.
At least, not in your lifetime. A few hundred years hence, your descendants will probably be considered French, but the nation identifies with bloodlines.
The names of the nations make that plain.
America has no such distinction. To put it in simplest terms, America and being American is based mostly on - an idea.
Come here, go through the process, raise your hand, take the oath - you're an American. As American as anyone else.
Depending on your nation of origin - some might have trouble with it for a while. After 9/11 they had that video where people of all types just repeated the same phrase - "I am an American".
America is based on an idea of what a country should be, and if it doesn't hold up to its ideal, it's still there.