There are thousands of places to find geospatial data on the web. Below are projects of the Cornell University Library that help organize and provide access to geospatial data.
Geolode is a collaborative catalog of geospatial open data websites around the world, searchable and browseable by location, topic, and other tags, so that searchers can quickly focus on the most relevant websites for their geodata needs. It was originally created by staff at Mann Library, and is maintained by a group of volunteers from several colleges and universities.
CUGIR, the Cornell University Geospatial Information Repository, provides free and open access to geospatial data for New York State, as well as worldwide geospatial data created by researchers at Cornell. CUGIR provides dataset descriptions and previews, and in addition to traditional data downloads, CUGIR also provides WMS and WFS web services for most datasets.
New York Historical Aerial Photos
Cornell IRIS has a collection of historical aerial photos covering nearly all of New York state from the 1930s to 1960s. Six counties have been digitized and are available online. A project is currently underway to digitize the complete collection photos of all counties.
New York State GIS Clearinghouse
The NYS GIS Clearinghouse provides a catalog of data from state, county, and local governments across New York State. Many datasets are freely available, while others require a Cooperative Member login. Cornell University is a member, so if you find any datasets requiring a login, contact Keith Jenkins (the Mann Library GIS Librarian) for access.
Olin Library Map Collection
Before there was GIS, there were maps. Olin Library has a extensive collection of over 650,000 paper maps, 4200 books and atlases, and 1000 data discs, representing information that often cannot be found online. Library staff can help you find and scan historic maps, or to access datasets on disc. The Map Room is located on the Lower Level of Olin Library.