Light rail service recently began in the Phoenix area. It runs from the East Valley through Tempe and on towards downtown. So far, it seems to be pretty severely underutilized. Last night, after the Bloc Party show, I had to wait at a light for an unusually long period of time because the train was coming. When it finally came, it was like a ghost train, completely empty. It occurred to me, though, that part of the function of such projects -- perhaps even the primary function, in the grand scheme of things -- is not so much to facilitate physical connections between different locations, but mental ones. Even people who have no reason or desire to ride light rail up here have been forced to confront its arrival as a visual and traffic-altering phenomenon. The line's presence reminds them that the place where they currently are is bound to Phoenix in a way that the roads sometimes do not. Right now, the map of the light rail system has not been learned by many. But I'm betting that, over time, it will become part of the mental geography of people in this area the way the maps for BART in the San Francisco Bay Area and METRO in the Washington D.C. area did. I was always struck, while riding both of those systems, that the places that fell outside the map, such as Vallejo, California, where I used to live, were consigned to a kind of psychogeographic limbo with negative consequences, both for their citizens' self-image and the perception of others. There were financial consequences too, of course. Vallejo would be a radically different place today if the people who ran its bus system had been unsuccessful in their bid to block BART from crossing the Carquinez. Then again, Marin County would be different, and probably not in a positive sense, if it had welcomed BART. Either way, though, Marin and Solano County exist in a different mental place for people who either reside in or visit the Bay Area than, say, Contra Costa County, which is prominently featured on the BART map despite being farther from San Francisco.