 US 31 goes through some more rural countryside before meeting the western terminus of SR 396 (Saturn Parkway) in Spring Hill and gains the name 1st Street.After leaving Spring Hill, US 31 has an interchange with I-840.US 31 then continues into Franklin, where US 31 Truck makes a turn to the east onto SR 397 (Mack Hatcher Memorial Parkway), while US 31, erroneously signed here as US 31 Business (which doesn't actually exist and US 31 mainline is signed throughout Franklin), passes north through downtown Franklin.