Evan Soltas
Mar 10, 2016

Did Michigan Vote Against Trade?

Paul Krugman writes:

The Sanders win defied all the polls, and nobody really knows why. But a widespread guess is that his attacks on trade agreements resonated with a broader audience than his attacks on Wall Street; and this message was especially powerful in Michigan, the former auto superpower. And while I hate attempts to claim symmetry between the parties — Trump is trying to become America’s Mussolini, Sanders at worst America’s Michael Foot — Trump has been tilling some of the same ground. So here’s the question: is the backlash against globalization finally getting real political traction?
It's certainly plausible that Donald Trump's and Bernie Sanders' strong performances in the Michigan primary are manifestations of a protectionist backlash. I was curious, and so using David Dorn's data on local declines in manufacturing and vote data from the Michigan Bureau of Elections, I checked.

The idea: To see if Trump and Sanders benefited from protectionist sentiment, I will compare their respective primary vote shares in a given county against how badly affected that county was by the decline of manufacturing employment.

The protectionist-backlash explanation of Trump and Sanders does not seem to hold up:

Here are vote-weighted scatterplots to visualize these conclusions:

By the way, I completely expected Krugman to be right on this one—and I remain quite surprised that the protectionist-backlash explanation isn't apparent in the data. But it's not. 

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Note: Dorn's data is actually at the "commuting zone" level, so I assumed that manufacturing declines were constant across counties within each commuting zone. I have data on 21 commuting zones and 83 counties in Michigan.

If you want to try to prove me wrong, I've made it easy for you: My pre-processed data are available here for download.