Find the name of route that has the lowest number of deliveries?
SELECT t1.route_name FROM Delivery_Routes AS t1 JOIN Delivery_Route_Locations AS t2 ON t1.route_id   =   t2.route_id GROUP BY t1.route_id ORDER BY count ( * )  DESC LIMIT 1
lowest number of deliveries refers to MIN(COUNT(*)); name of the route refers to route_name;