Advocating this is being a Devil's Advocate twice for me; I don't like the Spartans, and I think Jerry Pournelle was a fascist. But one who could write an entertaining story, in a twisted sort of way. And he of course has the Empire of Man run by New Sparta, a colony world founded in Co-Dominion times precisely to realize a Utopian vision that takes inspiration in part from Sparta itself. Also from neo-Classical economic theory and a whole lot of right-wing memes in general.
The point being, if we want to talk of a USA-scaled Sparta, we must be talking about a modernized Sparta, one run along completely different lines than the ancient one, one which is "Sparta-like" in the sense that what works about it and for it corresponds to what worked for the Spartans.
As noted upthread, the Spartans weren't really all that successful in historical perspective; they could no more make a pan-Hellenic hegemony work than the Athenians could. Worse actually, but on the other hand they were less inclined to try. Historically I guess their biggest success was that they managed to survive a while. And they impressed the hell out of a lot of swooning fans through subsequent history. But they were no Rome, no Alexander, no Han Dynasty, no Mohammed.
So why exactly was Jerry Pournelle among these swooning fanboys? I dunno, I guess it goes with being a certain kind of right-winger, to deplore Athens and praise Sparta. The Sparta he made the most stable and viable survivor of the collapse of the Co-Dominium and founding world of two Empires of Man doesn't look or feel a lot like Greek Sparta to me; it's mostly a romanticized version of 18th/early 19th century Britain, with I guess some universal military service tossed in.
Anyway that's how to do it, I guess, stretch the definition of "Sparta-like" just about beyond recognition.
FWIW if I were called upon to do this as a challenge, I'd make my moderized Sparta expies left-wingers, Communists or the like, stress the universal service meme to extend beyond military into every sphere of human action; enemies would denounce it as "universal helotry" but the Commie-Spartans would laugh that off.
In other words, do exactly the opposite of what Pournelle did.
