North Easterns

I live in a neighborhood where north Easterns are generally settled and I noticed all of them tend to hangout with north Easterns only. Even in my school ,where lot of North Eastern kids were there,they only hung out with north Easterns only despite us inviting our classmates they ignored and hung with their own kind only. I have north Eastern friends myself but they said some ppl just don't wanna deal with other states people.Is it true? If so why's that?