Free GM Resource: The New York Public Library Map Warper
The cool thing is this is a great Free GM Resource because it is a HUGE digital map collection that is being released under a Creative Commons CC0 1.0 Universal Public Domain Dedication license.
So far every post I've seen on the subject is just a re-hash of the press release, which made me take a closer look.
I love using old maps for inspiration on making new ones and this Open Access collection is a simple sign-up away. Registration took less than a minute and then I had access to this great collection. Seriously, the registration was little more than my name, email and password twice. No muss and no fuss.
The access to the collection is done through the Map Warper and I didn't quite know what to make of it at first. It is pretty easy to search for historical maps and once you find a map there is an "export" tab that lets you download a high-resolution image. A lot of the options, at least on the 1st map I tried were for "warped" versions, which makes some sense because I was using the Map Warper after all. I was a bit surprised to download my 1st map and see it all skewed up. Fortunately you can also download an un-warped TIFF.
It ends up you can do more than just find and download maps. The whole point of the open access is to be able to assist the library by essentially overlaying these old maps over current ones to be able to tell the differences between the two. In order to do that you have to "warp" the map.
If you do end up using the map in something you create, the library does ask that you attribute the work as "From The Lionel Pincus & Princess Firyal Map Division, The New York Public Library." While technically you don't need to cite public domain work.....well at least legally, it is a good idea to do so, especially here since this helps the NYPL track how their stuff gets used and probably helps them in fundraising for the collection.
You can click on the lead-in graphic to reach the collection sign-up page, or use this link.