I have a layer of impervious surfaces in the contiguous US, provided by the US Geological Survey as a WMS. The CRS is set to EPSG 4326, which is what the metadata says it should be. The entire layer is about 13 miles too far to the north. The east-west placement seems to be correct.
This is the service URL: https://smallscale.nationalmap.gov/arcgis/services/ImperviousSurface/MapServer/WMSServer
I've tested it with several different layers that I know are correct. Here you can see what it looks like with a Google Hybrid basemap (obtained through QuickMapServices plugin).
On-the-fly reprojection is turned on. The screenshots are from QGIS 2.18, but I have the same issue in QGIS 3.0.
Why is this WMS layer mis-aligned?
UPDATE: I downloaded a different WMS layer from the USGS (USGS Imagery Topo Base Map - Below 18K Scale Dynamic) and it's correctly aligned. This proves that: A) I am capable of correctly loading a WMS layer; and B) not all data from the USGS has this issue.