Washington was convulsed by accusations of spying, self-dealing and hypocrisy. Investigations multiplied.

It was 1924, and at the center of the anger and suspicion — fueled by government dysfunction and wealth inequality as gaping as it is in 2019 — were two millionaires.

One was the treasury secretary, Andrew W. Mellon, a financier and philanthropist and forerunner of Steven Mnuchin, a former Goldman Sachs executive who became President Trump’s treasury secretary.

Mnuchin is now the face of the administration’s quest to keep Trump’s tax returns from Congress. In a letter on Monday, he told House Democrats that he would not comply with their request to turn over the material, in a move that experts say could be contrary to a 1924 law stipulating that the secretary “shall furnish” such records to congressional committees. Mnuchin maintained that the request served no “legitimate legislative purpose.”

The story behind the 1924 law reveals how the currents creating chaos in present-day America reach back to the period before the Great Depression.

The law at issue in the strife over Trump’s taxes arose from a bitter dispute between Mellon and Sen. James Couzens (R-Mich.), a deep-pocketed adversary on Capitol Hill, over the lawmaker’s investigation of the IRS.

The tax feud became linked to the Teapot Dome Scandal, a bribery incident beginning in 1921 in which President Warren G. Harding’s interior secretary gave a political friend access to oil leases without competitive bidding.