The books the authors cite are great and worth reading. Some personal observations: - The USA lacks a unified cultural identity now. There are lots of reasons for this. But, it's considered taboo to express a love of the USA - which hurts our community + culture. - People put a lot of effort into work, and work is becoming more transactional. No more "life-long employment with the buddies" kind of situation. - Americ…
I don't disagree with the comment, but whenever people talk about a "love of the USA", I always want to ask what is it that you love? To stereotype a bit, I'm guessing that it will not be the federal government (despite a strong reverence for the flag of that government).
There are symbols which are more directly associated with the government, such as the Great Seal of the United States. You will see patriotic expressions involving that symbol rather less, although the bald eagle, our national totem, is quite popular.
Some countries have a separate state and civil flag. The United States is not among them.
If you're asking why Americans love our nation, I don't know how to answer that question.