We speak the same language, watch the same TV, share a federal government and use the same currency. That's pretty much all NYC has in common with most of America.

NYC is supposed to be the capital of American culture, but ironically we live closer to a European lifestyle than anywhere else. Typical American lifestyle is based on car culture, but NYers don't drive. So they don't live the same way day-to-day.

Robust mass transit and walkable neighborhoods are a part of NYC the way they are in Europe, because much of the infrastructure was developed in an urban expansion boom that occurred shortly before cars came to dominate American life. NYC also narrowly managed to resist some of the changes that swept other American cities, thankfully saved mostly by the complicated logistics of demolishing such heavily populated areas in favor of highways and parking lots.

The rest of the USA, being rural dwelling and mostly under-developed until the mid 20th century, got it's taste of urbanization at the time of the rise of automobiles. Since cars were the grand vision of the future, everything in America after 1945 or so was designed to support them as a way of life. NYC being already densely developed at that point, had no room for the big strip malls and drive-thrus that became central to Americans elsewhere.

So the culture of America after 1945 grew around cars in pretty much every corner of the country - except NYC and a handful of other urban centers. Part of that culture is chain restaurants because they are easy to spot when driving. Ditto for big box retailers. NYC is built around neighborhood, human-scale experience and the rest of the country is built on interstate, car-scale experience.

Because the gap is so jarring it also further isolated NYC from American life, to the point where many people who live even a few miles outside of the city have only ever visited a few times and vice versa. Adopting new transportation habits has a complicated learning curve and is scary to most people, so they keep in their comfort zone. The disconnect keeps growing and NYC becomes increasingly a more foreign tourist curiosity than anything, to average american suburbanites. But talk to NYers and that's how they see the world outside the city as well. It goes both ways.