45 and 46.
I’d say the erosion of states rights started, oddly enough, with prohibition.
If I remember correctly, criminals could flee to another state and there was no way for law enforcement to pursue criminals across state lines.
Hence, the creation of federal crimes and the FBI to fight such criminal activities.
From there Herbert Hoover, progressives, FDR, The New Deal, etc.
An encroaching federal government could have been fought by the States at that time. They didn’t, so, here we are now, having States fight the federal government.
Hopefully, the States can win the battle.
Once you have read that book, you will see that the erosion of states' rights began as soon as the Republic began doing business in 1789.