Why do many small town people never leave their small town?

I grew up in a small town but I did go to different cities with my family so I respect everyones racial religious and whatever other differences but people in my small town are terrified of cities and plan on staying in the small town for the rest of their lives. Many of these people's families have been here for generations. Many of them also have close minded views about lots of things. Why do many small town people never want to leave?