Yep, old houses actually made them that size, the mills kept making them undersize to get more from the log so they finally stopped at 1.5 x 3.5 for interchangeability sake.
It was driving people crazy when it came from different mills at different sizes, or so my grandpa told me.
I always thought it was 1 5/8” by 3 5/8”
Before kiln drying the mills cut to nominal 2”x4” sizes. That was from green unseasoned lumber. The differences in moisture content determined the final drier seasoned size. Didn’t matter much when finished walls were wood lath and plaster, plenty of room to make up the fractional difference. Gypsum drywall and kiln dried framing came along about the same time. First nominal std was 1 5/8” x 3 5/8” and that was true when I started wood framing. Wasn’t that long ago that it dropped to the current size. I grow old.
I did some renovation work on an 19th century townhouse in Manhattan, was a bitch putting in drywall with all the fractional shimming. In the end, plastering would have cost the client about the same.
And those studs and beams were tough as iron. Taking down wood lath horse hair reinforced plaster is nasty work. Metal lath also.
At any rate, this decision is more dumbing down of America. Took a long list of over educated ignorant soft folk to carry this stupid case through the court system. If you are unaware of nominal lumber sizing you should be playing with saws, hammers or nails, bound to hurt yourself bad.