I worked for a pro-vaccine organization on communications issues a coupled of years back.
That is why I found the Wisconsin section more than a bit strange and inaccurate, and which makes me think that responses and vignettes in Perry's travelogue on this and other subjects he covers have been edited to reflect his onw incorrect prejudices instead of being at least balanced anecdotes.
Why do I say this? Because the social science, and I dealt directly with it, shows that there is only a very small correlation with political beliefs and anti-vax nuttery, and if anything, Pew surveys and Yale cultural cognition studies have found the US left is over represented among those holding whacked out anti vax views.
And let's not forget this is a British infection that built this craziness. It was a British doctor, Andrew Wakefield, trained and practicing in Britain, and published by the top British medical journal, The Lancet (despite Lancet having had indications the research was bad before they published) that spread the major anti-vax quackery to the US, Canada and Australia.
In the end with Perry's travelogue we get the worst of British travel lit that has been evident for centuries -- a condescension and inaccuracy, that tells us more about the observer and nothing interesting or really valid about the subject.