This is the Abstract for a fascinating paper, “Highway to Hitler” by Nico Voigtlaender and Hans-Joachim Voth (NBER Working Paper No. 20150, Issued in May 2014)

Democracy is not an absorbing state; transitions to autocratic rule have been frequent throughout history and often followed periods of instability under democratic rule. In this paper, we ask whether autocrats can win support among voters by showcasing their ability to restore order and to “get things done.” We analyze a famous case – the building of the highway network in Nazi Germany. Highway construction began shortly after Hitler became Chancellor, and was one of the regime’s signature projects. Using newly collected data, we show that highway construction was highly effective in boosting popular support, helping to entrench the Nazi dictatorship. These effects are unlikely to reflect direct economic benefits. Instead, highway construction signaled economic “competence” and an end to austerity, so that many Germans credited the Nazi regime for the economic recovery. In line with this interpretation, we show that support for the Nazis increased particularly strongly where highway construction coincided with greater radio availability – a major source of propaganda. The effect of highways was also significantly stronger in politically unstable states of the Weimar Republic. Our results suggest that infrastructure spending can win “hearts” for autocracy when “minds” are led to associate it with visible economic progress and an end to political instability.

Trump’s popularity ratings may improve.

To some mental-health professionals, the debate over diagnoses and the Goldwater rule distracts from a larger point. “This issue is not whether Donald Trump is mentally ill but whether he’s dangerous,” James Gilligan, a professor of psychiatry at New York University, told attendees at a recent public meeting at Yale School of Medicine on the topic of Trump’s mental health. “He publicly boasts of violence and has threatened violence. He has urged followers to beat up protesters. He approves of torture. He has boasted of his ability to commit and get away with sexual assault,” Gilligan said.

Bruce Blair, a research scholar at the Program on Science and Global Security, at Princeton, told me that if Trump were an officer in the Air Force, with any connection to nuclear weapons, he would need to pass the Personnel Reliability Program, which includes thirty-seven questions about financial history, emotional volatility, and physical health. (Question No. 28: Do you often lose your temper?) “There’s no doubt in my mind that Trump would never pass muster,” Blair, who was a ballistic-missile launch-control officer in the Army, told me. “Any of us that had our hands anywhere near nuclear weapons had to pass the system. If you were having any arguments, or were in financial trouble, that was a problem. For all we know, Trump is on the brink of that, but the President is exempt from everything.”

From “How Trump Could Be Fired” in the New Yorker.