Expert Commentary

Massive collection of C-SPAN footage shows Congress members literally cross the aisle less than they used to

New research forthcoming in Political Analysis finds U.S. legislators have been literally crossing the aisle less and less since the 1990s.

(Darren Halstead / Unsplash)

When Sen. John McCain died last August, it wasn’t the first time and it wasn’t the last time that political watchers noted the end — or at least the severe decline — of bipartisanship.

Many remember McCain for crossing party lines on major legislation, like campaign finance reform, and for bucking fellow Republicans in 2017 on repealing the Affordable Care Act’s individual mandate. But a paper forthcoming in Political Analysis that examines legislators’ physical movements on the floor of the U.S. House of Representatives confirms that bipartisan socialization may be just about bygone.

Author Bryce Dietrich, an assistant professor of political science at the University of Iowa, analyzed the biggest video collection of the U.S. House of Representatives ever used in political science research — 1,413 hours, about two months’ worth of video, covering January 1997 to December 2012. The clips are overhead shots from cable network C-SPAN showing representatives’ movements about the chamber.

Dietrich found representatives have physically crossed the aisle less and less to interact with opposing colleagues over time since the late 1990s. The ideological rift in Congress began in the 1970s and mirrors a broader partisan split in America over recent decades, according to the Pew Research Center.

“Anecdotally, reporters and members of Congress have all noted this, so to be able to say with some rigor now there is evidence, I think that’s important,” Dietrich says.

Republicans and Democrats were more likely to vote along party lines when representatives didn’t interact much on the House floor with opposition members, according to the paper. The less physical movement on the House floor after a vote — the more that representatives mostly mingled within their ideological ranks — the more likely that party line votes would follow later the same day.

This simulation represents Democrats and Republicans comingling on the House floor. (Bryce Dietrich)

“Where there’s a highly polarized environment, that influences the degree to which they are willing to signal to one another that they want to cooperate in a bipartisan manner,” Dietrich says. “One way of signaling bipartisan cooperation is by literally walking across the aisle.”

Congress is a small world where social interactions matter when it comes to which bills become law. For example, senators tend to vote on a given bill the same way that other senators in their college alumni network vote, according to a 2014 paper in American Economic Journal: Economic Policy.

House members can reap legislative benefits when they sponsor bills with representatives from the opposing party. A bill sponsored by representatives from both parties can help bring representatives on board who might have opposed a similar bill sponsored strictly along partisan lines, according to a 2011 paper in the Journal of Politics.

This simulation represents Democrats and Republicans staying among their ideological ranks on the House floor. (Bryce Dietrich)

Yet, until Dietrich’s forthcoming paper, researchers largely had not tapped into one the biggest datasets on how House members interact — video footage of the floor — and the outcomes of those interactions.

“The best thing about Congress is C-SPAN has documented it since the ‘70s, so there is a wealth of resources,” Dietrich says. “This paper will hopefully get people to think about how to leverage that resource for social science questions.”

Part of the reason C-SPAN footage hadn’t been analyzed is that software and computing power wasn’t, until now, up to the task of processing massive amounts of video. In conducting his study, Dietrich evaluated more than 70,000 video clips. Over time, the frames gradually become structurally similar — Democrats tend to stay more on their side of the aisle, Republicans on theirs.

It’s not just how House members mill about than can indicate their intentions. The emotional intensity of Congress members’ floor speeches maps to their commitment to the issue they’re talking about, suggests new research from Dietrich and Matthew Hayes and Diana Z. O’Brien of Rice University, published in the American Political Science Review.

Even Supreme Court justices seem to telegraph their decisions based on how emotionally intense their voices are during oral arguments, according to a 2018 study by Dietrich with Ryan D. Enos and Maya Sen of Harvard University. Video motion can provide an important compliment to voice analysis, Dietrich writes in the forthcoming paper.

“There’s this tapestry of congressional behavior,” Dietrich says. “Until recently we didn’t have the tools to look at research questions in this area.”

Dietrich was a postdoctoral research fellow from 2018 to 2019 at Harvard’s Shorenstein Center on Media, Politics and Public Policy, also home to Journalist’s Resource.

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