Each vertical pillar represents a state that has ratified the new government. In this cartoon, North Carolina’s pillar is being guided into place (it would vote for ratification in November 1789). Rhode Island’s pillar, however, is crumbling and shows the uncertainty of the vote there.
The illustrator is trying to convey the message, that the Constitution’s strength depended on unity. Each pillar stands for a state, and together they support the new government. The crumbling Rhode Island pillar warns that without all states, the system was fragile.