In Mapping Experience, Marc Treib uses the London Underground map to show how maps are diagrammatic - "clear, articulate, and legible--all the things that London as a city is not." After reading this section of the article, I instantly remembered the wikipedia representation of Amtrak's North East Corridor route, designed by wikipedia users. It is certainly all the things that the North East Corridor is not. There is also no notion of scale - nor is there the "east" directionality, but rather only the "north." Although Treib describes the two dimensionality of maps as a limitation, I think this extreme example of a one dimensional map demonstrates perfectly how the limitation can be a benefit. The train passenger certainly feels this linearity while riding, especially during the portion of the trip that travels directly beside I-95 N.