Running away form parents? Who gets custody?
Mother will get custody unless the father establishes a suitable home right away and asks for equal placement. This is usually hard to do if the family was living in a home that consumed a substantial share of the monthly budget. If your dad can get a decent apartment, and wants the kids half time, he can usually get that if he requests it immediately. then you have the one week there, one week at mom’s kind of arrangement. If dad goes to live in a small apartment someplace while mom and he get things figured out, then the kids usually stay with mom until dad has a place they can visit. then the standard practice is to have the kids with dad every other weekend, and each wed evening for a few hours after school. This is the standard practice in parts of the US. Every case can be different, so a lot depends on what your parents want to have happen.
Don’t run away. If you run away you’ll be homeless until the cops find you, and then you’ll be turned over to whichever parent wins custody. In some states they can even arrest you for running away. I guess you could try to get legally emancipated, but that’s probably not a good idea. You’d have to support yourself financially, purchase your own home, etc. Your best bet is to live with whatever parent is awarded custody. I don’t know how old you are, but you’re probably too young to survive on your own. And if not, just wait a few years until you’re 18 and you can move out anyway.