Add this one to your list of primary source resources. The Collaborative Digitization Program is a project begun by the Colorado State Library that stives to achieve high quality digital access to cultural heritage collections. Their focus is on the American west. Partnering with museums and libraries throughout the west, the project highlights best practices for digitzing, archiving, indexing, and storing historical content. The collections include historic newspapers from Colorado, primary source material from Heritage Colorado and Western Trails, and an architectural collection documenting architectural styles dating back to the 1850s.
The Teacher Toolbox includes dozens of lesson plans for all grade levels, as well as self-paced professional development to help teachers with searching for and utilizing photographs, maps, audio and other media.