My question is: What age can a child decide which parent they wish to primarily live with? My son is 13 and he wopuld like to live with his me (his Dad). I am considering an out of State move and he would like very much to go with me. Any help I can get would be appreciated.

This might sound like a drastic measure but if you got the child his own solicitor, this person would make sure that the child's wishes were taken into account.

The child can not just "decide" the parent he wants to live with will have to make a motion to the court to have custody given to them.
Then the child will be allowed to testify as to who they want to live with, but it is still up to the judge to decide.

And of course the child support issues will also have to be settled

It's different here in UK. I have a young grandson living with me. The judge said, "The child has voted with his feet." Which I thought was a wonderful way to put it.

It depends on your state child custody laws. In some states being that your child is 13 yrs old they will ask your child's opinion and take it into consideration when they make their decision. Check your state laws. Call the county clerks office for the website.