DJ, when Javitz was first elected to Congress in 1946, I believe that the NY-21 comprised Washington Heights, part of Harlem and part of the Bronx, most similar to Rangel’s NY-15 among today’s CDs: here’s a very interesting Time Magazine article about the 1944 special election in which Torrens (whose surname is Catalan, by the way, but perhaps he was an Irishman with a Spanish ancestor from the days of the Invincible Armada) narrowly defeated an old Republican who had served in Congress prior to WWI (!), with the Republican carrying the district’s Harlem precincts. Of course, maybe that special election was the last one held under the old lines and when Torrens was reelected in November 1944 (and when Javitz was elected in 1946) the district no longer included Harlem, since I recall that it was in 1944 when they finally redistricted in NY (for the first time since 1922 IIRC) and they finally drew a black-majority district in Harlem, which elected Adam Clayton Powell that year.
Oopd, forgot the link to the 1944 article: http://www.time.com/time/magazine/article/0,9171,932363,00.html