It seems a little unusual for a junction sign to indicate both a business route and a parent route. But there's an explanation for this sign assembly in Trenton. It's actually on Missouri 6 eastbound. Just behind this sign is the intersection with Business US 65, going off to the left on Oklahoma Avenue. Then, for a very short distance, not even 100 feet, Business US 65 and Missouri 6 are concurrent until they reach the US 65 interchange (you may be able to see the bridge for the interchange even farther in the background). So this sign assembly actually is indicating two junctions immediately ahead. They're so close that it probably makes more sense just to combine the assemblies as has been done here.