Missouri Secondary State Route YY is a short north-south spur off of Missouri State Route 124 in Central Boone County. MO Sec St Rt YY does not pass through any towns in Boone County. MO Sec St Rt YY is not multi-plexed in Boone County. MO Sec St Rt YY intersects the following highway in Boone County. Missouri State Route 124, near Harrisburg.
