We spent more than a year examining the AR-15’s role in America. Here’s what we learned.

To understand the AR-15 and its impact, The Washington Post interviewed more than 200 people with expertise or relevant firsthand experience — including firearms industry executives and lobbyists, gun owners, shooting survivors and victims’ families, lawmakers, trauma surgeons, first responders, activists, armed militants, academics and ballistics experts, among others. Our examination also relied on a review of thousands of pages of documents, including internal company records, court and regulatory filings, and autopsy reports, many of them obtained through public records requests. And, in the most detailed poll of its kind to date, The Post partnered with Ipsos to survey hundreds of AR-15 owners about their reasons for having the weapon.

Here’s what we learned:

A flip by the gun industry: The AR-15’s rise over the past two decades was sparked by a dramatic reversal in strategy by the country’s biggest gun companies to invest in a product that many in the industry had long viewed as anathema to their culture and traditions. The industry embraced the gun’s political and cultural significance as a marketing advantage as it looked for new revenue. Manufacturers rode a post-9/11 surge in military admiration while also stoking a desire among new gun owners to personalize their weapons with tactical accessories. Gun companies seeking to rebrand the AR-15 have used images of police and soldiers wielding tactical rifles in the field, urging civilian buyers to, as one ad put it, “use what they use.”

Spikes in consumer demand: While handguns account for the most gun-related killings in the United States, sales of AR-15s surge in times of tragedy and political change. They soared in the run-up to the election of Barack Obama in 2008, and after the mass killing at Sandy Hook Elementary School in 2012 and a high school in Parkland, Fla., in 2018, and again ahead of the turbulent 2020 presidential election. AR-15s, which once accounted for a small fraction of guns produced in the United States, now represent nearly 1 in 4, according to industry and government figures.

Who owns AR-15s and why: About 1 in 20 U.S. adults — or about 16 million people — own at least one AR-15, according to new polling data from The Post and Ipsos. Self-defense is the most popular reason for owning one, with many respondents also citing recreation, target shooting and hunting. Compared with Americans as a whole, AR-15 owners are more likely to be White, male and between the ages of 40 and 65. They’re also more likely than adults overall to be Republican and to live in states Donald Trump won in 2020. The industry, meanwhile, has shifted operations in many cases to more culturally welcoming terrain. Numerous firearms, ammunition and gun accessory companies have moved headquarters or production facilities from liberal to conservative states, where communities see the companies as sources of jobs, not controversy.

The gun’s brutal efficiency: The AR-15’s mechanics, which allow shooters to easily fire bullets at a high velocity in rapid succession, make the weapon lethal and destructive. When the bullets penetrate the body, they create a blast effect that blows up organs and pulverizes bones. The weapon’s power magnifies the impact of gun violence, both because of the number of victims and, for survivors, the long-lasting effects on physical and mental health. In Sutherland Springs, Tex., where more than two dozen people were killed during an eight-minute rampage in 2017, the additional 20 people injured continue to grapple with debilitating, lifelong conditions such as paralysis or infertility. More than 90 percent of gun-related homicides involve handguns, according to the FBI, but 10 of the 18 deadliest U.S. mass killings since 2012 have involved AR-15s.

A recurring American nightmare: The full effects of the AR-15’s destructive power are rarely seen in public because governments often restrict access to crime-scene photographs and news organizations are reluctant to publish images that might retraumatize families or dehumanize victims. But a review of newly gathered witness accounts and photographs from some of the country’s deadliest mass shootings reveals a repeating pattern of devastation in which familiar places are instantly turned into zones of gruesome violence.

Escalating arsenals: In response to years of right-wing violence and intimidation linked to the AR-15, some far-left activists have begun to form armed groups, billed as community defense, often turning to the AR-15 as their weapon, as well. Some leftist activists who long favored nonviolence have grown more tolerant of armed support at public events as threats against the LGBTQ community and other vulnerable groups rise and faith in law enforcement recedes.

Outgunned police: Police departments that once deferred to SWAT teams wielding military-style rifles for active-shooter situations have started equipping officers with AR-15s and other long guns, as those weapons have flooded the neighborhoods they patrol. Many officers welcome the change, some buying their own AR-15s and using them for sport. But police often say they still feel outgunned and ill-prepared — hampered by a lack of training and by public demands that they do everything possible to avoid using force.

A path to fewer deaths: Many gun violence experts and law enforcement veterans say that restricting the sizes of ammunition magazines would lessen the carnage caused by AR-15s and other guns. Smaller capacity magazines would force shooters to pause during their attacks to reload, allowing people to flee or fight back, research shows. Most states do not limit magazine sizes, but in the past year, four states have capped them at anywhere from 10 to 17 rounds. Such efforts face growing legal challenges, and the issue could ultimately wind up before the Supreme Court.

A gun that’s too easy to get? The April 2023 shooting at the Old National Bank in Louisville, carried out by a gunman experiencing mental health problems, highlighted a larger debate over whether there should be additional limits on who can purchase a semiautomatic rifle — particularly when it comes to troubled young men who gun industry critics say are often the targets of marketing campaigns built around masculinity, military imagery or sex appeal.

About this series

Reporting by Hannah Allam, Holly Bailey, Mark Berman, Shawn Boburg, Sarah Cahlan, Manuel Canales, John Woodrow Cox, Josh Dawsey, Todd C. Frankel, Silvia Foster-Frau, Jon Gerberg, Emily Guskin, Arelis R. Hernández, Alex Horton, Nate Jones, N. Kirkpatrick, Robert Klemko, Joyce Lee, Atthar Mirza, Ashley Parker, Elyse Samuels, Isaac Stanley-Becker and Jon Swaine. Photography by Jabin Botsford, Lisa Krantz, Joshua Lott and Jim Urquhart. Videos by Jon Gerberg. Motion graphics by Osman Malik. Design and development by Anna Lefkowitz, Tucker Harris, Aadit Tambe, Rekha Tenjarla and Shikha Subramaniam.

Lead editors: Peter Wallsten and Wendy Galietta. Editing by Kainaz Amaria, Scott Clement, Karly Domb Sadof, Tim Elfrink, Amanda Erickson, Ann Gerhart, Matea Gold, Rosalind S. Helderman, Philip Rucker and Debbi Wilgoren. Additional editing: Jordan Melendrez, Kim Chapman, Brian Cleveland and Tom Justice. Design editing by Madison Walls, Matthew Callahan and Virginia Singarayar. Photo editing by Natalia Jimenez, Robert Miller and Monique Woo. Video editing by Angela M. Hill. Graphics editing by Chiqui Esteban.

Additional support from Courtney Beesch, Brandon Carter, Alice Crites, Brian Gross, Bryan Flaherty, John Harden, Stephanie Hays, Meghan Hoyer, Frank Hulley-Jones, Jai-Leen James, Agnes Lee, Sarah Murray, Angel Mendoza, Andrea Platten, Tyler Remmel, Bishop Sand, Kyley Schultz, Ashleigh Wilson and Irfan Uraizee.