As a native of Washington State, I can say it’s a little more complicated than that. In Wash, and Or. there is a great divide, called the Cascade Mts. The greater population in both states and in Cal. as well, the West side of the Cascades has the larger population centers and where the d’RAT’s have settled. On the East side of the Cascades is where all the agriculture is located with a smaller population. City people tend to vote d’RAT while farmers tend to be conservative Republicans.
This means that if these states want to succeed, the border would have to be along the Pacific Crest Trail on the summit of the Cascade Mts.
Here in Washington we often thought that the State should be two states, West Washington and East Washington. We are so diametrically opposite in social and political beliefs.
You make an excellent point and I completely agree. There are significant differences between Eureka and LA; Bend and Portland; and Seattle and Spokane.