Talk:OpenHistoricalMap/Projects/Newberry Atlas of Historical County Boundaries Import
Coordinate System
Looking at the source data, it's stated "Dataset projected from GCS_North_American_1983 to GCS_WGS_1984, using NAD_1983_To_WGS_1984_5 Geographic Transformation."
Without trying to explain everything all over again, importing this without reprojecting it will have the same "offset" issue that existed in the original TIGER boundary imports... the short version is that while the original NAD83 was "intended" to be the equivalent to the original WGS84, it's actually not on the scale we map things in OSM, due to the way NAD83 was created. Please see How to transform data from NAD83 to WGS84.
The "fix" would be to undo the WGS84 -> NAD83 transformation in QGIS, then follow the process described on the other page, using the NADCON 5.0 transformation grids to place the data on NAD83(2011) before converting back to WGS84(G2139). Without this, the import will have systematic 1-2 meter errors based on the "biases" in the original NAD83. Revent (talk) 22:50, 7 January 2024 (UTC)