New Yorkers can become obsessed in the minutiae of this city. Where and why else would you find a nine-page article on the typeface used in subway: "The (Mostly) True Story of Helvetica and the New York City Subway" (see story here)? The use of Helvetica is now the official typeface for the New York Subway system, but only recently. In 1966, the subway's design group, Unimark International, headed by Milanese graphic designer Massimo Vignelli, originally chose Standard (aka Akzidenz Grotesk) as the official typeface. Helvetica later crept into the system for technical reasons.
To any curious individual riding a New York City subway, it does not take much time at all before they will begin to wonder about the letter and number designations for the numerous lines. Are they all used? Which are, which are not and why?
As one might expect, many have gone into great depth of study over these questions. However, I was shocked to learn that every letter and number in use in the NYC subway system has its own individual Wikipedia page. A separate page discusses unused New York City subway service labels. Currently, 17 letters of the alphabet are being used and nine letters are not in use: H I K O P T U X Y.
How technical or nerdy do you want to be? By making a distinction that some of the unused letters do appear on the flipdots/rollsigns of the R32/R38 subway cars or the side signs of the R44/R46 cars (they may not be officially used, but could be displayed and may occasionally be by accident)?
Recently on a trip back from Brooklyn, in a fortuitous moment, I saw the F and G trains pass by (albeit in reverse alphabetical sequence). So I have begun to wonder, what is the longest string of trains one could see in alphabetical sequence without riding?
The West 4th Street station services the A, B, C, D, E, and F. One could, with a fair amount of stair sprinting, see and photograph all six trains in letter sequence. Or try to ride all the New York City trains in letter and/or number sequence. A noble mission for Sesame Street, perhaps, but my ride on this train of thought ends with the F and G :)