Submitted by our resident repository of Chicago transit map knowledge, Dennis McClendon, who says:

This map of Chicago’s rapid transit network originated in the 1970s (this one is from June 1983), and this style was used until routes received color names in 1993. Happily, by that time digital printing in fiberglass-embedded signs made full-color maps easier to place in graffiti-prone environments.

These maps were silk-screened onto [blue] color blanks, and every color of ink added cost. So the CTA’s six lines are represented by using only two colors. Simple black is used for three “extension” lines that never overlap. A simple white line is used for the north-south line those connect with. For the two other through routes: black with white casing and white with black casing.

The side ticks for stations work fine, but a box for the places where transfers are possible is not altogether intuitive.  The CTA of that era employed skip-stop spacing, so alternate trains stopped at A or B stations only. Another graphic decision that might have deserved more thought:  the names of various suburbs—only a few of which can be reached by rapid transit—floating in their vague geographic positions, but no indication of Chicago city limits or Lake Michigan.

Transit Maps says:

I have to say that I actually really like the forced graphic simplicity of this map. There’s only two colours to work with, so every element has to be very carefully considered and balanced against others for the map to work at all. That it manages to keep the route lines recognisable and separated in the downtown Loop area without the use of an inset map is quite an achievement.

The famous “A-B” stopping patterns are shown pretty deftly as well, being mostly placed on the opposite side of the route line from the station name. The few stations where this doesn’t happen (due to crowding or space limitations) stand out like a sore thumb – Jarvis on the North-South line, and many of the stations on the Ravenswood line. There are also two stations with their labels set at an angle: Merchandise Mart is almost completely unavoidable, but Harvard on the Englewood Line could easily have been fitted in horizontally.

I think the “boxed” interchanges work well enough, having seen similar devices on quite a few maps (the Paris Metro included) now. I also like the extra detail included on the map: station closures on weekends and nights, direction of travel around the Loop, inbound boarding only on the last three stations on the Jackson Park North-South Line, and more.

I would agree with Dennis on the locality names, that just seem to float in space. The biggest offender is “Evergreen Park”, right at the very bottom of the map, below the legend!

As for depicting Lake Michigan, that seems like a good idea, but I struggle to think of a way of doing it without upsetting the delicate balance of the map. You can’t really use a white line, as that could be confused with all the white route lines, and you can’t have a large white area as that would be visually way too heavy. In the end, the lake isn’t that important for such a graphically stylised map (it really just delineates the eastern side of the map), so I’m not too upset by its absence.

Our rating: A fine historical example of how to use a limited colour palette effectively. Minimalist but still effective. Three-and-a-half stars.