Missouri Secondary State Route O is a short north-south highway in Northern Bollinger COunty. Parts of this runs in the Mark Twain Forest. MO Sec St Rt O does not pass through any towns in Bollinger County. MO Sec St Rt O is not multi-plexed in Bollinger County. MO Sec St Rt O intersects the following highways in Bollinger County. Missouri State Route 72, near Patton.