It’s right on the tip of my tongue, a gruesome gloomy non-fiction about settlers - Minnesota? - on the great plains going mad and killing themselves. Not a recent book, not a scientific work with statistics and footnotes. Maybe with photos. The word ‘death’ is in the title, I think.
The BoxCar Children?
I kid i kid
Ole Rolvaag’s Giants in the Earth? “An award-winning, epic novel of Norwegian immigrant homesteaders in Dakota Territory.”
Little House on the Prairie?
?
That’s it, ‘Wisconsin Death Trip’. Thank you, problem solved.
Woo hoo, I got one! 
Yeah, makes much more sense than my guess.