The 17th Amendment was the Death Knell of the Republic. all sorts of corruption entered on the scene
The 17thA was 1913, and a lot of damage to the Republic occurred around that year, like the creation of the FED.
I’d argue that the death knell can be traced earlier than that.
E.g., the Act of 1871 and the incorporation of the District of Columbia.
Actually, it was the 16th, 17th, and 19th amendments that are collectively killing this country. Fortunately, the 18th amendment was repealed.