Federalist No. 9
Federalist No. 9, authored by Alexander Hamilton under the pen name Publius, is the ninth of 85 essays. Titled "The Union as a Safeguard Against Domestic Faction and Insurrection", Hamilton discusses tiny states within Italy and Greece as proof of the negative results of state hostilities and cautioned against repeating the same mistake.
It was published on November 21, 1787.
In the essay, Hamilton discusses the topic of tyrannies within republican forms. He quotes Montesquieu at length from his The Spirit of the Laws, that "it is natural to a republic to have only a small territory, otherwise it cannot long subsist." Montesquieu argues that a certain kind of republic, which retains the advantage of monarchy could be possible as a Confederate Republic. Hamilton makes the point that under the Constitution, America is exactly what Montesquieu described.
Finally, he discusses the decentralized nature of the proposed Constitution. While the Constitution does set up a strong government, capable of honoring and executing the enumerated powers delegated to it, most powers reside with the states. This is an attempt to work against Montesquieu's observation of republics spanning great distances, as each state is a relatively small area. Decentralized power is also a preventative measure against the tyranny of centralized forms.
In short, Federalist No. 9 highlights just how important the states are in the design of the Constitution.