Yes, but these studies came a bit late in the game, really.
My speculation is the US practice may have been based on:
(1) the masturbation hysteria of the late 19th/early 20th centuries (and may I say quite confidently that Kellog’s Corn Flakes, or Graham Crackers, reduce masturbation only during the specific time that you are actually eating them due to the crumbs-on-your-lap issue …
). As hinted at in an earlier post, the point was that the circumcised male would find ir, erm, “rougher” to masturbate w/o the extra material at hand.
(2) “hygienic” concerns – that really tied in to how, during that time period, much of the population did not exactly bathe that much. Now, it’s true that proper care and cleanup is not that difficult and takes care of most hygienic/aesthetic concerns, but then we fall again into (1) again – the Powers That Be did not want the kids paying too much attention to fiddling about with that part of the body in the first place, so let’s make it as maintenance-free as possible. (I’ve heard a bit of anecdote that this “maintenance-free” element was much influenced also by the deployment of so many Americans to the insalubrious trenches of WWI. However the Europeans were in those mudholes for 3 times as long, and went on as usual.)
2(a) another “hygienic” concern was the idea that the uncut prepuce created additional grounds for breeding and communication of venereal disease, at the time considered a major Public Health threat. Of course, the real reason if any for this was overall bad hygiene to begin with, but hindsight is 20/20
2(b) yet another was prophilactic attention to phimosis (the constricted foreskin that afflicts a significant % of various population groups). Thing with this is that, as tanookie has noticed, for practical purposes newborns are all phimotic and you can’t really tell at that point if they’ll need it. But if it needs to be resolved as an adult through surgery, that hurts like crazy.
(3) There would have been a religio-cultural component here, but not necessarily Jewish – let’s remember the USA “heartland” is (stereotypically, but stereotypes are based on something) very fond of its Bible’s Old Testament. So regardless of what Paul says about it in the NT, there they found that this surgical procedure, that at the time was advocated by the doctors, was also very favourably looked-upon by God. So, easy acceptance.
(4) Then (my hypothesis) it became generally known as the “modern” thing to do and acceptance spread even further and faster.
Nowadays I agree it’s cultural inertia