"In the 1960s, the New York subways were a mess, sign–wise. Station names and metro lines were spelled out in a hodgepodge of sizes, shapes, and styles. The original mosaic tiles had been joined by cut stone and terracotta–all of which clashed with newer enamel signs. They were not only inconsistent in terms of style but also in where they were placed, so straphangers didn't know where to look for directions on how to get from point A to point B.
In 1970, following the merger of the IND and BMT lines, the Metropolitan Transit Authority (MTA) hired Massimo Vignelli and Bob Noorda, designers at the firm Unimark, to put an end to the typographic chaos. The system they devised still informs signs made today and is painstakingly outlined in a 174–page manual"
(Belinda Lanks, 15 September 2014, Businessweek)