This is a piece of the 2016 Presidential Election that I am still trying to figure out...
The Dairy Industry has been hurting significantly in recent years as a result of declining agricultural commodity prices and have increasingly shifted towards exports of products overseas to help compensate....
Unlike the US Manufacturing sector, agriculture in general and dairy in particular would have been net beneficiaries of TPP, which Clinton initially helped negotiate and then backed away from during the '16 Democratic Primary, while Trump used TPP as a whipping post to tie Hillary Clinton to unpopular Free Trade Agreements, or perhaps more accurately the growing critique of the long-term impact of "Free" Trade agreements that has caused a significant amount of economic pain in many different communities throughout the United States.
Additionally, the dairy industry is suffering from a shortage of labor and increasingly reliant on immigrant labor and a Latino workforce to run the milking machines and other jobs in heavily rural counties, where the Anglo population is increasingly aging, and many of the local youth either move away to regional or Metro centers, or have no interest in "milking cows"
The two major dairy producing regions of Oregon both swung heavily towards Trump:
Tillamook County---- both in the actual rural dairy precincts within the county, as well as in the City of Tillamook, famous home of the Tillamook Cheese Factory.
Coos County---- Once we remove the Blue-Collar cities of Coos Bay/North Bend, take the more touristy Bandon out of the mix, we see a similar collapse in Democratic support in just the rural "dairy cow" precincts within the County.
Flip over to the 2nd largest Dairy Producing State in the US, much more significantly politically than a handful of heavily dairy producing regions of Oregon....
Look at what happened in Wisconsin!!!!
Considering how extensive dairy production is in Wisconsin, it's difficult to pull up any individual county or even region for comparative effect (Maybe one of our resident Wisconsin experts can break this down in fuller detail?)
Regardless, it's patently clear that there was a huge collapse of Democratic support in Dairy Country in Wisconsin from '12 to '16....
Scroll down to the bottom of the slidedeck in the link below to see the counties that produce 75% of "milk" in the United States....
http://hoards.com/sites/default/files/Intel/150803/Images/150803_5-dairy-maps.pdf