Shooting in Kansas City is the latest violence to spoil a sports celebration

Last June, 10 people were shot dead during festivities the night the Denver Nuggets won the National Basketball Association title. In 2019, four people were shot during the NBA championship rally for the Toronto Raptors. Two men were shot dead in a Los Angeles suburb during a celebration of the Dodgers' 2020 World Series victory.

This week brought the latest example of violence marring a festive sporting moment. On Wednesday, shots rang out at the end of a Super Bowl victory parade in Kansas City, Missouri, killing one woman and wounding at least 22 people. The bloodshed prompted Kansas City Mayor Quinton Lucas to wonder whether the city would hold another parade if the team won again.

“If we're blessed enough to win another Super Bowl, will we do it again?” Mr. Lucas asked during one interview with KMBC, a local news station. “Or do we all just say, 'Go to Arrowhead Stadium, walk through metal detectors' – do we have a highly secured, much smaller event?”

The vast majority of sporting events and championship celebrations take place without any overt violence. But some high-profile examples in recent years have led to growing discomfort among some that sporting events are becoming less safe. While there is little data available on the exact number of violent incidents in and around sporting events each year, researchers say several factors contribute to this feeling.

One of these is the large number of people involved. For example, a typical NFL game draws about 70,000 spectators. Larger crowds naturally increase the number of interactions that can lead to violence, says Tamara Herold, a criminal justice professor at the University of Nevada, Las Vegas, who researches crowd control and violence at sporting events.

“Audience density matters quite a bit,” said Dr. Herold.

The NFL has security at official events, such as games including the Super Bowl and the Pro Bowl, and at the annual draft, with a “control center” that monitors the venue and even monitors online conversations to quickly respond to disruptions. These events are also held at locations with security checkpoints that screen for firearms.

But parades and other championship celebrations are not official competition events. For example, the parade in Kansas City went through the heart of the city and attendees did not have to pass through any security checkpoints.

The availability of alcohol, extreme heat or cold, and even the importance of the game in question (for example, a Game 7 of the World Series) can also be exacerbating factors for violence, said Dr. Herold.

Stephen Billings, a professor at the University of Colorado business school who studies crime, said the fact that more aggressive behavior was taken for granted at sporting events — where people often drink alcohol and shout — could also contribute to such outbursts.

“If the norms are different from the typical norms in society, and people feel like they have the right to do something, then we also have conflicts,” he said.

And the effects can extend beyond locations. From research by Dr. Billings found that violent crime within a quarter mile of locations in Charlotte, NC, increased on game days between 2005 and 2009, compared to days when there were no games.

Over a four-year period, regular-season games in the National Hockey League were associated with an increase in attacks in host cities of about 10 percent, according to research by Kristina Block, a doctoral candidate at Sam Houston State University. More research from Ms. Block, co-authored with Jacob Kaplan, a researcher at Princeton University, found a 7 percent increase in crimes against local public order during NHL home games

Steven Block, a professor of criminology at Central Connecticut State University, investigated approximately sixty incidents of fights between fans in stadiums in North America. Paper from 2017. Often the fights were motivated by rival team loyalty, involved alcohol, and were defused by other spectators, not stadium security.

Dr. Block also emphasized the role of density.

“Just because of the sheer numbers, people may not feel like there is safety,” he said. “They feel like they are on their own, both to act aggressively and to defend themselves.”

After the 2013 Boston Marathon bombing, cities increased surveillance and began sharing more information about how to prevent another attack. But those efforts focused on the threat of terrorism, not the kind of violence that spontaneously erupts.

Nevertheless, Dr. Herold that the vast majority of sporting events were safe, and that the violence Americans heard about was an exception.

“When these things happen, they are tragedies,” she said. “But they are still relatively rare events.”