I finally stopped calling the blank spot on my 1850 county map a mistake
I used to think the empty wedge in the northeast corner of my 1850 atlas was a printing goof, until I compared it to an 1843 survey plat at the Indiana State Library and saw the same gap. Turns out that land was still tied up in a treaty dispute, so mapmakers just left it bare, and now I want to know if other county maps from that decade show the same kind of hole.