User blog comment:JCC the Alternate Historian/How Jefferson Would've Likely Voted in Past Elections/@comment-25626-20191225164624/@comment-25626-20191225222859

@JCC-Initially, I think it would be CA only, as they have the larger population (a very quick review shows 944,050 people bothered to vote in CA in 1920, versus the 244,000 or so who bothered to vote in Oregon), and so removing a Representative from CA in 1919 would be the path of least resistance. Obviously, that would be fairly moot in short order, as CA still grows more or less at the rate they did in OTL.

Changes to OR would be more gradual--people wanting to go to Portland or Salem might decide they'll have better luck in Port Orford or Yreka. So by the 1970s or so, you might see that Oregon is "missing" something.