The Times FYI column posted a question we've always wanted to ask:
Q. Most subway stops’ names use only the street number (42nd Street, for example). How come West Fourth Street and a few stops in the Bronx (like East 180th Street and East 149th Street) are given an east/west distinction?
A. Mainly to avoid confusion.
Herb Schonhaut, manager in New York City Transit’s Office of Station Signage, said the Fourth Street station uses the word “West” to distinguish it from the planned but unbuilt “South” Fourth Street Station in Williamsburg, Brooklyn.