Historical USGS Maps hosted by MapTech.
I was told: "We still have to put up the final image maps for the "new" states, and there are a few minor formatting errors that need to be cleaned up. However, it is ready for public consumption."
When Chris Marshall has some time to send out updates, Ohio, West Virginia and Virginia will go online, as will part of Indiana. Steve Titchenal scanned Ohio and what of Indiana he could find, plus some overlap with some of what I scanned, since he's using a higher resolution. I scanned most of Virginia and West Virginia, about half of Maryland, and a fringe of Pennsylvania. On my next trip to State College (maybe I'll go Saturday) I should fill in some alternate editions in PA, and fill out the missing coverage of Virginia, then see what else is available.
I'm about due for some ice cream anyway.