My best shot is: Per Septentrionalia, Patria Nostra. Literally, it means, "Throughout the Northern (Regions), Our Fatherland". The great strength of this translation is that "upper peninsula" in Latin would be something like "Paeninsula Supera", and so this preserves, to a limited extent, the "U.P." wordplay by creating a first phrase which has the same "P.S." initials.