Spur Route 45 branches off from Missouri 45 about three miles east of Leavenworth, Kansas. Spur 45 provides a direct route to the Missouri River bridge at Leavenworth. You can tell the markers on this assembly are rather worn; the state outline has begun to peel off the sign blanks.
Missouri state maps indicate another Spur Route 45 in Platte County going into the town of Waldron, but I did not see it marked, at least in the northbound direction on Missouri 45, when I traveled through the area in September 2005.