Yeah, the northings and eastings.
By chance are you using a parcel fabric dataset? There are some good workflows out there for adjusting a parcel fabric based on known reference points / adjustment links.
We have quite a lot of "bad data" spots like this in our parcel data, for all kinds of reasons. (Look up the "Indian Boundary Line" related to the Chicago Portage / I&M Canal for one of them.)
The way we are working on this issue is to review our surveys, plats, and monument record documents on record and pulling out any PLSS corners with coordinates. We have been mapping those corners as points.
Once we have two adjacent PLSS corners with good coordinates, we can draw a township/section line between them, and we know that all parcels along this boundary (unless otherwise specified in their legal descriptions) should align with it.
Performing the adjustment itself can depend on the size of the offset. If it's only a couple feet, I will simply snap my parcel features to the line. If it's a bit larger, as in your post, you'd want to somehow distribute the adjustment across multiple parcels proportionately. That's where the parcel fabric tools, such as the aptly-named Adjust Parcels, come in particularly handy, but there are other ways to do it, too.
- Josh Carlson
Kendall County GIS