That is the question Gary Lawson (Boston Univ. School of Law) attempts to offer an answer in One(?) Nation Over-Extended [SSRN]. Here’s the abstract:
The conventional wisdom prior to the founding was that republics needed to be small. The conventional wisdom today is that James Madison, and the example of the United States, proves this to be mistaken. But what if Madison was actually wrong and Montesquieu was right? In this article, I consider whether the United States has gotten too big for its Constitution, whether this massive size contributes to political dysfunction, and what might be done to remedy the problem if there is indeed a problem. I suggest that size can increase rather than decrease the dangers of faction because the increased returns from control over a large territory can swamp the transaction costs of building a winning coalition. The obvious solutions are a decrease in the size of the national government, an increase in the costs of constructing winning factional coalitions, or a breakup of the United States into smaller, more manageable units. The first and second options are unfeasible, and the third (secession) is unconstitutional even if feasible.
Interesting. — Joe