Throughout the series, universal values, issues, and dangers abound, such as_ mixed marriage, culture shock, racism, the right of self defense and to be armed, the threat of the power of the public mob, the threat of strong government, the conquest of minority races in the 19th. Century, and much more. For example, in the latest book, America purports to be helping the Filipinos become independent from Spain but then conquers the Philippines after the (fairly modern, Christian, non-savage) natives succeeded in defeating Spain without much help from us.
Interestingly, the series reveals how liberal and conservative goals can meet in libertarian-minded people such as my Navajo/white married couple.
[Part of this post is from the author's comments on Goodreads reader/writer site.]