  st. james is a hamlet and census-designated place (cdp) in suffolk county, new york, united states. the population of the cdp was 13,338 at the 2010 census. st. james is part of the town of smithtown and is located on the north shore of long island. the zip code is 11780. ==history== in the early 20th century, st. james was a popular vacation spot for glitterati of the stage and screen. summer residents included lionel, ethel, and john barrymore, buster keaton, myrna loy, and irving berlin, among others. {
Census-designated_places_in_New_York Census-designated_places_in_Suffolk_County,_New_York Smithtown,_New_York