Spur Missouri 240 branches off from US 40 and Missouri 240 in Howard County, providing a route into the Boone County town of Rocheport. However, Spur 240 does not go all the way to Interstate 70, on the other side of Rocheport. Instead, it ends in downtown Rocheport, where it "becomes" supplemental Route BB.
Unusually, the Spur banner went below the route marker on this sign assembly, photographed in September 2005.