Changing the license value for the Atlas of Historical County Boundaries. https://digital.newberry.org/ahcb/downloads/index.html now states the Atlas can be "reused for any law purpose, commercial or non-commercial, with licensing or permission fees to..
OpenHistoricalMap is a project designed to store and display map data throughout the history of the world. This is a work in progress, we'll be playing around with many new features as we time-enable the site. We encourage you to start playing around and editing data, too.