Like most things there is a book that looks into this. Take a gander at the Wikipedia if your interested (the author argued that there are 11 'nations' in the US). https://en.m.wikipedia.org/wiki/American_Nations

Living in the Washington, DC area, it was always frustrating how outsiders would treat us like our city was exactly the same in makeup, attitude, and general culture as New York City, and would then judge our stuff based on that. First, no, New York City is not like DC. Second, no, the main difference between New York City and DC isn't that DC is a bunch of government drones. There are other jobs. It's a whole ass city? It has local economies, artists, food places, software firms, everything you'd expect. Third, New York City pizza isn't good. Stop acting like because a pizza deviates from that standard, it means the pizza is bad. AND I KNOW WHAT I SAID, FITE ME. Finally, we don't have a subway. We have a metro rail. And it's well laid out and easy to navigate, and when you reach your station stop it's easy to get a bus for the final leg of your journey. It's a superior metro scheme because the trains can operate at 60 mph, whereas the top speed for the subway where the trains must act both in place of the trains and the buses is 40mph.

Now to wait for the angry hate comments to come in...

Why were you and your buddy in the shower together though?

Born in the south and moved to Philadelphia in my early twenties. It was more culture shock than some other countries I’ve been to. Folks in Philly don’t hold back. If they don’t like you they tell you, to your face. They also don’t feel the need to add all the extra and often unnecessary pleasantries to every social interaction. Honestly for a “well mannered” southern kid it was pretty liberating to get to drop all that.

"even" you say. I live in a not small but not that kind of a big country and you get out of the coastal cities and you end up in whole another culture. I don't know the exact reasons but where sea exists, I feel home. 150-200 kilometers outside is completely different. I guess in my country, where people originally came from has to do with this topic. Coastal areas generally has people from Europe, other areas from Eastern countries, etc.

I think you’d be surprised about how much of a cultural difference there is in NJ in itself

I'm from a European country and you can drive 30 miles in the same country but there's already another language or different dialect that you hardly can communicate and they have 1000years old traditions and celebrations totally different from your own area

Completely agree. I grew up in the Dallas area and spent 3 years in Colorado Springs. The "coffee culture" of the area was shocking to me. I had a roommate sit me down and tell me I needed to stop wearing camo pants because it looked ridiculous, while it was fairly common back home. There's so many little things that are different that you don't realize until you're in it.

I saw a thing with Hugh Laurie not too long ago and he said something like, "America is too big to even know itself. Someone in Georgia has no idea about the day to day life of someone in Oregon."

I've been thinking about that a lot lately.

Why would this be surprising?

You can get wildly different cultures between neighbors living on the same street in the same town.

*in America

It sometimes gives me mild existential dread thinking about how you can never really know that many places. I live in New York City and in 15 years I still feel like I barely know the surface. If I wanted to know Chicago or DC or Houston or Portland, what chance do I have? What can you learn in a week or a month? And even if I moved there now I'd never know what it was like as a kid, a teenager, a young adult. I doubt I could really know each of their subcultures, too.

I think the differences between a wealthier, urban individual from different parts of North America (ie LA/SF vs NYC or Chicago) are smaller than the differences between someone who lives a rural life in California or Oregon vs someone who lives in upstate New York or rural Pennsylvania.

While there are definitely cultural differences related to the history of an area and the peoples who occupied it, money and privilege that come with an urban life tend to blur those lines a bit more.