The GOP has owned the US South, winning a majority of the region's votes in every presidential election for the past 40 years. But it wasn't always this way.

The so-called "Solid South" used to vote reliably Democratic. So what happened? Most scholars believe it was backlash to Civil Rights legislation of the 1960s.

Still, even today, the question is not completely settled.

Researchers Ilyana Kuziemko and Ebonya Washington used Gallup poll data available through Cornell University's Roper Center to investigate the role that racial attitudes — as opposed to economic concerns — played in Southern whites' defection from the Democratic party. Their paper published in the American Economic Review in October 2018 concludes that whites' backlash to the Civil Rights law explains almost entirely the shift toward the Republican Party.

Kuziemko and Washington spoke with the AEA after their paper was published about how their research contributes to our understanding of voters' motivations during that period and why researchers need to be careful about connecting that experience to today's political environment.