I have tried Googling 84th St. + New York City; New York City neighborhoods; boroughs of New York, 1940's. I got mostly travel information and ads for maps and atlases. I also tried a recent Fodor's guide for the city (couldn't find one from the time), but couldn't get much more than a rough idea of where the street is. Can anyone help?
ETA: Thanks to everyone for all your help. It sounds like 84th St. in Manhattan, pretty far to the west of Central Park, would fit my guy better than anything else. I appreciate y'all's prompt assistance!