Political rallies stir passions, but do they impact the results at the ballot box and ultimately on policy choices? Those are the questions underlying a new research paper co-authored by Harvard Kennedy School Assistant Professors David Yanagizawa-Drott and Daniel Shoag. The paper, titled “Do Political Protests Matter? Evidence from the Tea Party Movement,” is published in the Quarterly Journal of Economics.

Yanagizawa-Drott, Shoag, and co-authors collected data from a variety of sources to test their theories relative to a specific case – the so-called “Tax Day Protests” sponsored by the Tea Party on April 15, 2009. The research resulted in several key findings.

“We show that attendance at this initial event had significant consequences for the subsequent strength of the Tea Party movement, it increased public support for Tea Party positions, and it led to more Republican votes in the 2010 U.S. House of Representatives elections,” Yanagizawa-Drott writes. “The protests had a nation-wide effect on the 2010 elections corresponding to an estimated 3.2-5.8 million additional votes for the Republican Party.”

The data also showed that policymaking was also impacted, as incumbents responded to the large protests by voting significantly more conservatively in Congress.