The Oregon KKK came very close to running the state in the early 1920s, boasting many members in the legislature - including the Speaker of the House, the synchronicitously named Kaspar K. Kubli - and helping elect Walter M. Pierce as governor in 1922. However, they kind of became victims of their own success. Their signature legislation, a ban on private elementary education targeting Catholic and Jewish schools, was struck down in a
landmark Supreme Court case. Furthermore, their ally Pierce was an incompetent, which tainted the brand - as did the Klan's involvement in municipal corruption scandals in Portland. The state branch vanished pretty quickly after that.
Here, the KKK succeeds in their original 1922 plan, successfully primarying anti-Klan incumbent Ben Olcott in the Republican primary. Pierce, a political opportunist, ignores the "school question" and plays the moderate. While he wins, he turns out to be just as incompetent as IOTL and the Klan successfully organizes a recall. Allegations of voter fraud swirl, but now the KKK is in the ascendant and has the political scene cowed. In 1926 they take the governorship outright, and proceed to establish a stranglehold on both political parties while perpetrating all the usual despicable shit you can expect from the Second Klan.
Most voters don't care about the racism, of course, but they do care about the graft, which is ridiculous even by Roaring Twenties standards. And even if the DC Stephenson case is butterflied, there's bound to be some other gross scandal that turns mainstream white America against the Klan. So in 1930 the eccentric, liberal-minded cattle king Bill Hanley sweeps in from Harney County to clean things up. Hanley's not in the greatest health, though, and he dies while still rooting out white hoods in the civil service. Of course, this just so happens to be as the big waterfront labor disputes are heating up, and Hanley's Secretary of State and constitutional successor just so happens to be the good-government Jewish department store owner, Julius Meier. An establishment scared of communists realizes that they've got an army of willing foot soldiers in all these recently fired Klansmen, and General Iron Pants decides he wants to stage a March on Salem.
This isn't Wilmington in 1898, though, and the feds intervene right quick, arresting those too stupid to keep their noses clean. I imagine the little in-character blurb being written by a newspaper editor desperately hoping the BOI doesn't notice how many times his name appears in Henry Failing Cabell and Charles Martin's conspiratorial correspondence.