WUE = Western Undergraduate Exchange.
Basically, less selective public universities in the western region of the US offer residents of other western region states tuition that is 1.5 times in-state tuition, instead of the usually much higher out-of-state tuition. Details vary by school, since some may allow only students in some majors to use this tuition discount.
Website: https://www.wiche.edu/wue
Search for schools: http://wue.wiche.edu/search1.jsp
All schools: http://wue.wiche.edu/search_results.jsp?searchType=all
Note that some WUE schools have additional criteria beyond residency in a western region state. For example, Colorado State University mentioned above has specific GPA and test score requirements for frosh who want to get the WUE discount: https://financialaid.colostate.edu/scholarships-for-entering-non-resident-freshman/