The (Mostly) True Story of Helvetica and the New York City Subway
http://www.aiga.org/content.cfm/the-mostly-true-story-of-helvetica-and-the-new-york-city-subway

Shaw, Paul
AIGA
2008

Abstract:

There is a commonly held belief that Helvetica is the signage typeface of the New York City subway system, a belief reinforced by Helvetica, Gary Hustwit’s popular 2007 documentary about the typeface. But it is not true—or rather, it is only somewhat true. Helvetica is the official typeface of the MTA today, but it was not the typeface specified by Unimark International when it created a new signage system at the end of the 1960s. Why was Helvetica not chosen originally? What was chosen in its place? Why is Helvetica used now, and when did the changeover occur?