For years, NGS hosted its digital map collection on an FTP site. It was a treasure trove of historical geodetic maps and indexes. In January I realized that the link I had posted from my site to the NGS FTP site no longer worked; communications with NGS indicated that the FTP site is down indefinitely while they work to hire a web developer and content manager, who will then reorganize the site and make the historical content available once more. Maybe. Maybe within the next few decades. (No offense to NGS, but I know firsthand how historical digitization projects are a low priority for many organizations.)
In the meantime, I have posted the files here: NGS Historical Geodetic Control Diagrams
My sincere appreciation goes to David Grosh at NGS, who downloaded, prepared and sent the files to me.