DISCLAIMER: I am not a historian nor a political scientist. I do have a fascination and interest in the Constitution and so I started reading the Federalist Papers and posting my interpretation on my own blog. I thought it might be of some interest here. Your interpretations and thoughts are greatly appreciated in the comments!
You can find the Federalist Papers in their entirety at The Library of Congress website.
Federalist No. 13 and links to previous Federalist Papers entries below the fold and previously posted at LiveJournal
Federalist No. 1 here
Federalist No. 2 here
Federalist No. 3 here
Federalist No. 4 here
Federalist No. 5 here
Federalist No. 6 here
Federalist No. 7 here
Federalist No. 8 here
Federalist No. 9 here
Federalist No. 10 here
Federalist No. 11 here
Federalist No. 12 here
Advantage of the Union in Respect to Economy in Government
For the Independent Journal.
This is a relatively simple argument for a union of the whole United States - division into smaller confederacies will take just as much government by each of the confederacies as that of the entire union of the states.
In the beginning, Hamilton makes the point that it would be cheaper to pay for a single government as opposed to multiple confederacies:
If the States are united under one government, there will be but one national civil list to support; if they are divided into several confederacies, there will be as many different national civil lists to be provided for--and each of them, as to the principal departments, coextensive with that which would be necessary for a government of the whole.
He then states that no one would support 13 sovereign state confederacies. However, there was discussion about division into 3 geographical confederacies - 4 Northern states, 4 Middle states, and 5 Southern states. Hamilton then notes that each of these confederacies would be larger than Great Britain and that it would take a large government to properly manage a confederation of such size - one as large as the one proposed in the Constitution for the union of all the states.
Civil power, properly organized and exerted, is capable of diffusing its force to a very great extent; and can, in a manner, reproduce itself in every part of a great empire by a judicious arrangement of subordinate institutions.
Hamilton then goes on to say that division into the 3 confederacies would likely cause the middle states to align with the northern states and therefore subjected to TWO governments. Essentially the nation would be divided into northern and southern factions. This would result in strengthening the northern states against the weaker southern states.
Hamilton closes by saying the union of the states would be best able to support a national government than any division. He says this as an obvious fact. He then closes out the paper by reiterating some of the arguments from Federalist No. 12.
we shall clearly discover that a separation would be not less injurious to the economy, than to the tranquillity, commerce, revenue, and liberty of every part.