First off, I want to say how silly I felt typing "walla walla wa" into Google Maps to find out exactly where it is. No offense intended, but yeesh!
Walla Walla is as of 2071 in Salish-Shidhe Council territory, near but not on the border with Tir Tairngire (the border appears to be I-84). There's a fairly good summary write-up in Sixth World Almanac, but the Cliff's Notes version is that it's not so much a nation but a collection of nation-states. There is a governing council which creates federal laws, but each individual tribe is more or less self-governing with its own set of laws. So laws and enforcement can change drastically within just a few miles. It's also very accepting of metahumans and those affected by SURGE, becoming a sanctuary during persecution of those two groups. AR is spotty outside major cities, and the shadow community is thin due to the lack of a lot of corporate interests in the country (Seattle is in the middle of Salish-Shidhe, so it's more of the hub of shadow activity for the area). Bellingham is the capital and Vancouver apparently has a small but active shadow community.
I'd have to dig up my old Native American Nations book for more info, but it doesn't look like there's a lot of canon info on Walla Walla. Which means you can make it whatever you want it to be pretty much.