Is it illegal to runaway if you are almost 18?

It is only explicitly illegal for minors in nine US states (Georgia, Idaho, Kentucky, Nebraska, South Carolina, Texas, Utah, West Virginia and Wyoming).

However, nearly every state allows police to take runaways into custody and return them home without a court order or the minor's permission. Habitual runaways can be taken to court for a "Child in Need of Supervision" process.

Even in states where running away is not illegal, adults helping a minor (either by facilitating running away or providing shelter) may be considered to be "harboring a minor", a misdemeanor offense.