Pink is the color of the Chicago Transit Authority's new train line. The exact hue has not been announced but the color was selected after a review of about 500 essays from Chicago area students. The pink line will launch on June 25th and service Chicago's west side and western suburbs.
I believe that Chicago is the first major U.S. city to identify a transit line as pink. Most U.S. cities have opted to use numbers, letters or location rather than colors. Pink is more commonly used in transit systems in other parts of the world including London, Brussels, Tokyo, Paris and Mexico City to name just a few.
Happy Riding Chicago!
PS- If you have a fascination with metro systems you may be interested in a new book "Metro Maps of the World" by Mark Ovenden.