There are a multitude of reasons why people move from one location to another just as there is a myriad of reasons some people choose to live close to where they were born. Society of course is now much more mobile and international involving patterns of migration and immigration. Oops, we're talking about humans here not animals.
I grew up in the suburbs of Boston, Massachusetts, which while a kid I assumed was the center of the universe. I lived within a small community which was rather homogeneous with few visible signs of minorities, religious, cultural or otherwise. I was aware that certain ethnic groups had their predictable stereotyping, however grew up somewhat insulated within a Catholic upbringing where most people were of European descent. It was only later in life that I began to realize how self reinforcing it can be living amongst the same type of people as myself with only small amounts of variance. Middle class people living in a similar environment can be rather featureless in the larger picture of things.
When people make a decision to move away from what's familiar to them they take the inherent risk of experiencing something different than what they might be used to.It may involve a job opportunity somewhere else, moving to a different climate, or being near (or away) from family.Relationships may also be a factor, wanting to live near someone we love or the hope of romance and socialization.
Such a melting pot our country has become, although I'm fairly certain there remain some isolated areas that do not experience much change. When moving into a new community it is an adjustment trying to figure out how the locals do things. I'm a dead give away because of my accent. I often get comments "you're not from around here are you?" When I encounter people who grew up in the south I often have a difficult time understanding them if they have a thick accent. I think it is probably challenging for southerners to move to other areas of the country without being noticed as talking different. I think I kind of know how they feel. It must also be rather noticeable when a "Yankee" moves down south.
Do people ever develop that deep sense of loyalty and identification to a region they move to in adulthood after growing up somewhere else? Although I have resided in northern New York for 24 years I still feel like a transplant and unless you were born and raised "here" you'll always be considered an outsider by people who have generational longevity. So when someone asks me where I'm from I say I live in northern New York but grew up in the suburbs of Boston.