I was struck, several months ago, by a piece in The Times about the effort to create a new interactive map of the New York City sewer system. For nearly a decade, the Bureau of Water and Sewer Operations – a branch of the Department of Environmental Protection – has been scanning its archive of old engineering maps onto what will soon be a digital map of the system.
Most of those old maps are covered with notes about changes and updates to the system, as are the tens of thousands of index cards that also record field data about the grid beneath us. Some of those maps and cards date back a century and a half, and the system they describe – 6,000-plus miles of pipe – is both a study in sober city planning and a miracle of improvisation.
Most of us will never get to use the result of all this underground mapping – after all, it’s sensitive information. But we do get to use the surface map of the city that was created to provide a reference grid for the Department of Environmental Protection’s subterranean map. (It can be found at http://gis.nyc.gov/doitt/cm/CityMap.htm.)
At first, NYCityMap feels a little clunky, especially if you’re used to navigating in Google Maps. But what’s interesting are its hidden dimensions. With a few clicks, you can pull up an unbelievable wealth of information about any address or neighborhood. You can find the nearest greenmarket, the year of construction on almost any building, the record of restaurant inspections in the neighboring blocks, etc. In other words, the surface map is really a map to all the maps hidden within it. It is an extensive municipal guide to New York City, organized geographically.
There is a pleasing logic to this kind of organization, to layer after layer of data embedded within a scalable map. In a sense, it approximates how we tend to know the world.
Think of returning to your neighborhood after a trip or driving to your parents’ house. You can almost feel the increasing depth of your knowledge as the terrain becomes more familiar. What you know isn’t just the superficial arrangement of streets and highways. You have a rich array of geographically organized information, some of it practical – how far to the good grocery store – and some of it emotional.
It’s easy to assume that the real revolution in mapping is the global positioning satellite and Google revolution – the ability to pinpoint yourself in real time on a digital map using G.P.S. technology and to move effortlessly around the globe, at increasing levels of detail, as you can in Google Maps and Google Earth. But the real revolution lies in the layering of data onto these already kinetic methods of viewing the world. In a very real sense, the virtual planet becomes our index to what we know about the actual planet.
Curiously, this shift in the information that maps contain only heightens the romance of what I can’t help calling flat maps. I think of one of my favorite maps of all time – the old AAA map to what it guilelessly called Indian Country, the Navajo Reservation and the Southwest. The map itself is an evocative piece of work – somehow far more suggestive of the resonance in that rugged landscape than most maps usually are. But I like my copy because it was my dad’s and because I can visualize so many of the roads that trail across it and because I kept a mileage log, from one cross-country trip, in the margin.
What we gather in maps is shared information, and what we take from them is, so often, personal. And that is their beauty, whether they are digital and overlaid with information or flat. Sooner or later you drive off the edge of the map you’re using and into your private knowledge of the world around you. The maps that will never be drawn are the ones that live in our own heads.
I could, if I put my mind to it, lay down a map of all the fencing on my farm, where the posts stand, where the wires intersect, where the electricity enters and where the repairs are needed. I could map out the circular spots where the pigs have lived over the years, as if they were ancient settlements. But in the end I would only be mapping it for myself, and the map I need is already in my head.