Missouri Secondary State Route O is a north-south highway in West-Central Knox County. It runs south of Missouri State Route 6 into rural Knox County. MO Sec St Rt O does not pass through any towns in Knox County. MO Sec St Rt O is not multi-plexed in Knox County. MO Sec St Rt O intersects the following highway in Knox County. Missouri State Route 6, near Hurdland.