Maybe, but I think the transition from a representative democracy to oligrachy for the U.S. happened some time during the 20th century. 1913 is a popular time for that transition because of the 1913 federal reserve act passed by Woodrow Wilson:
https://en.m.wikipedia.org/wiki/Federal_Reserve_Act
https://en.m.wikipedia.org/wiki/Crit...ederal_Reserve
The great depression is often blamed on this act and similar volatile market recessions benefiting the wealthy elite at the expense of the general public that followed afterwards. However, the transition to an oligarchy could of possibly happened earlier or later and more gradually and for different reasons.