im 19 i live in Alabama my girlfriend is 17 and she lives in tennesee so what concent age do we go by? the tennesee 4 year apart as long as shes not 13 or under? or the 16 consent age in alabama?

The law of the state you are physically located in at the time of the sexual intercourse, is the law that presides. If you are in Tennessee, the laws in Tennessee have jurisdiction. If you are in Alabama, the laws in Alabama have jurisdiction. If you are crossing state lines to have sexual intercourse with a minor, or a minor is being transported or aided to be transported across state lines without a parents consent for the purpose of sexual intercourse with an adult, there may be a federal violation in which case federal law would take jurisdiction initially, and there is potential that state laws would also be enforced after rulings on the federal violations.