I found an error in the shapefiles for historical county boundaries. Specifically, the border between Butte and Yuba County CA is wrong from 1860 - 1900. What is the source for the historical county boundaries in NHGIS, and is there any way the errors in it could be rectified?
Dear Jim,
We used William Thorndale and William Dollarhide’s Map Guide to the U.S. Federal Censuses, 1790-1920 as our main source of historical county boundaries. The authors created county maps that align as best as possible to the boundaries that were in existence for each decennial census. This was done to support the work that genealogists do tracking their ancestors.
The maps depict current day county boundaries, and then for each decade, they use a black line to indicate that year’s boundary. I looked at the California county boundaries for those decades, and I see a small difference between the current day and historical boundaries. But it’s quite difficult to tell what the difference was.
If you can send examples of what you think the boundary should be to NHGIS@umn.edu, we can put the correction on our list of shapefiles updates.
Sincerely,
Dave Van Riper
IPUMS