Rhody--- welcome again to the Forum!
I know I already did that on your second post and discussion on the 2016 elections in Rhode Island, but just want to say again how rare it is to get new posters jumping in off the bat with significant contributions, and a brain teaser
on your sixth post no less!!!!
So regarding San Juan County, New Mexico....
I confess I'm not particularly well versed on the Political Geography and Demographics of New Mexico, but it was a very interesting question, so I spent an hour or so trying to look at the Census Data and precinct level returns (Which are available for recent elections on the County website), since the more one looks at the county, the more interesting it becomes and stands out....
So I'll attempt to render my limited and humble opinions, and hopefully someone with more background will jump in, like one of resident New Mexico/ SW political experts, or someone more versed in the subject than myself....
1.) Political voting patterns appear to be heavy polarized between majority Anglo communities and those precincts that are located on the Reservation (~ 20% of the County Population). Off-Reservation precincts tend to vote overwhelmingly Republican (~80% in '16). This is not totally uncommon in the Mountain West, where frequently there is a long history of land conflict between the First Nations, and the Farming/Ranching settler population (See Montana/ North Dakota/ South Dakota for similar type examples.
2.) The Navajo Nation precincts tend to have a significantly higher level of Republican support, than many other First Nations/ Native American "Reservations" in many other parts of the country. I did a brief survey going back to around 2004 Pres GE results, and it looks like Republicans tend to bag about 25-30% of the Reservation Vote, even though Census Data appears to indicate that the New Mexico portion of the Reservation is almost 100% Native... (I'm slightly skeptical on the Census Data here for multiple reasons... but still).
3.) Voter Registration and Turnout appears to be significantly lower on Reservation precincts than off-Reservation precincts. This is not unusual on Native Land for a variety of reasons, but one of the big Civil Rights voting issues when it comes to the sovereign First Nations, is the the inaccessibility of voting precinct locations. There have been a ton of lawsuits in various parts of the country on this various subject, but obviously something like Vote-by-Mail (VbM) tends to make rural voting much more accessible, especially in some of the poorest rural areas, where many people don't have reliable transportation and can't afford the gas money to drive to some remote voting location.
4.) The age demographics of the County.... Anglos are a plurality of the population at the 45-54 Year age range (48.2%), jump to 57% (55-64), 60% (65-74), 63% (75-84), and 73% (85+ Years).... Considering that 23% of the population is 55+ this is significant....
Meanwhile 30% of the population is under the age of 18.... These numbers run only about 30% Anglo.... (Old New Mexican Spanish might identify as Latino or White for Census purposes). An additional 24% of the population are voting age Millennials (18-34 Yrs).... It is notably that 3rd Party voters captured 10% of the vote here, with the vast majority voting Libertarian.... something tells me most of these voters weren't in the 45+ age bracket.
5.) It's really not clear to what extent the Off-Reservation Native population votes Democratic at a Presidential level.... Looking at the data something close to 30% of the population of overwhelmingly Republican Farmington is Native American, and yet is still votes Republican by insanely overwhelming numbers.
There is also the history of assimilation in the Eastern part of the Navajo Nation (New Mexico) that included other items beyond the standard genocidal practices of the Settler population, namely destruction of the traditional patterns of communal land ownership and establishment of private property rights.
http://www.nec.navajo-nsn.gov/Portals/0/NN%20Research/Psychosocial/2007_%20migration_%20assimilation%20and%20the%20cultural%20construction%20of%20identity-navajo%20perspectives.pdf6.) I could go out on a limb and also note that the county is 9% LDS and there is a significant energy sector element to the local economy, from Coal Mining to other activities that accounts for 31% of the Navajo Nation revenue... Still, there have been Mormons and energy extraction in San Juan County for over a Hundred Years, but
honestly I don't believe this argument and it doesn't past the basic logic test, other than perhaps a few % point swing among Native Voters.... The County has been voting overwhelmingly Republican for decades, well before the "Energy Wars" of the 2000s, and many poorer and working-class Mormons in the Mountain West tended to vote Democratic until a few short decades back.
Anyone else want to chime in with other insights?