To my mind, this denotes a tournament consisting completely of strong grandmasters. In that sense, about the only tournaments in the US I can think of offhand that qualify would be the two Piatigorsky Cup tournaments (Los Angeles 1963 and Santa Monica 1966), probably New York 1924 (despite the presence of Edward Lasker), and possibly Dallas 1957 (not as well known, but a field of Gligoric, Reshevsky, Szabo, Larsen, Yanofsky, Olaffson, Najdorf and Evans is not to be taken lightly).

Events such as New York 1889, Cambridge Springs 1904, and, for that matter, San Antonio 1972 are closer to "mixed" tournaments. All featured a large number of first-class players, but also a number of weaker ones. At San Antonio, for instance, you had several IMs, such as Donald Byrne, Kaplan, Campos-Lopez, and Saidy, as well as Kenneth Smith.

I wouldn't put Dallas 1957 in the "supertournament" category because I think Evans and Yanofsky were too far down on the rating list. I would add New York 1927 to the tally of US "supertournaments," with Capablanca, Alekhine, Spielmann, Nimzowitsch, Marshall, and Vidmar.