In yesterday’s New York Times Book Review, Yale librarian Fred Shapiro pointed out that he’d found a 1948 use of the sociological acronym WASP, nine years before the previously known earliest source. The term appeared in the New York Amsterdam News on 17 April:
In America, we find the WASPs (White Anglo-Saxon Protestants) ganging up to take their frustrations out on whatever minority group happens to be handy — whether Negro, Catholic, Jewish, Japanese or whatnot.The writer was Stetson Kennedy, one of the main figures in Rick Bowers’s Superman vs. the Ku Klux Klan, which I reviewed for The Horn Book. At the time, Kennedy was on an anti-Klan crusade, and reports to New York’s leading African-American newspaper were a natural part of that. Within a few years, McCarthyism would drive him to Europe.
That also pushes the term back toward World War 2, when everyone knew WASP stood for Women Airforce Service Pilots.