How the New York Public Library digitizes its vast map collection

While much of the city's mapping community is focused on creating something new, a great deal of energy also goes into recovering maps that are quite old.

The New York Public Library, the spiritual heart of the city's mapmaking community, is gradually putting online its vast collection of 435,000 maps. Using a software program called "Building Inspector," more than 1,000 users are manually inputting information or checking contained on old maps that computers can't easily handle, such as street addresses. It's arduous work—only 33,000 of the library's maps have been digitized—but so far the volunteer army has completed 1.2 million tasks and helps the library to bring old maps online much faster than it could otherwise.

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