The economic costs of Democrat “dictatorship” in the South before the passage of 1965 Voting Rights Act: Hard data

When talking about one-party "democracy", what usually come to our mind are Singapore, Malaysia, Japan, etc. But United States had such experience too, before the passage of 1965 Voting Rights Act (which eliminated poll taxes, literacy tests, etc). Prior to the act, it was impossible for Democrats to lose any elections in American South.

Recently, economic data reveal that Americans living in the south suffered a lot from such “dictatorship”.  Several economics professors, Timothy Besley (LSE), Torsten Persson  (Stockholm) and Daniel Sturm (Munich) examined the history and found that:

By their  bottom-line estimate, the increase in political competition triggered by the Voting Rights Act raised long-run per capita income in the average affected state by about 20 percent, and the quality of Governors went up significantly.

Competition is always good!

Political Competition and Economic Performance: Theory and Evidence from the United States
Abstract: We formulate a model to explain why the lack of political competition may stifle economic performance and use the United States as a testing ground for the model’s predictions, exploiting the 1965 Voting Rights Act which helped break the near monopoly on political power of the Democrats in southern states. We find statistically robust evidence that changes in political competition have quantitatively important effects on state income growth, state policies, and quality of Governors. By our bottom-line estimate, the increase in political competition triggered by the Voting Rights Act raised long-run per capita income in the average affected state by about 20 percent.