Fires at two ballot drop boxes that destroyed hundreds of ballots in the Pacific Northwest this week, as well as a similar fire earlier this month, have raised questions about the role and security of drop boxes in the upcoming election.

Although drop boxes were widely adopted across the US in the 2020 election during the Covid-19 pandemic, Oregon and Washington have long relied on the method for conducting their elections. In those states, most voters use drop boxes to cast their ballots, and election officials there are closely familiar with the systems and their security.

“There is thought and effort put into securing every method of ballot return, whatever that is,” Tim Scott, the elections director for Multnomah County, home to Portland, Oregon, told CNN.

Here’s a look at how and why drop boxes are used, the efforts in place to ensure their security and how Oregon’s most populous county has handled its drop box security.

The how and why of ballot boxes

The ballot drop box is exactly what it sounds like – a box for voters to drop completed absentee or mail ballots.

They serve as a “secure and convenient” way for voters to cast their ballots, according to the US Election Assistance Commission, a bipartisan agency established by the Help America Vote Act of 2002. In particular, voters can deliver their completed ballots to a drop box without needing to rely on the mail service.

“These voters may be motivated by lack of trust in the postal process, fear that their ballot could be tampered with, or concern that their signature will be exposed,” the commission explains. “Voters may also be concerned about meeting the postmark deadline and ensuring that their ballot is returned in time to be counted.”

For election officials, drop boxes also improve voting access and lower the number of people who need to access voting locations, giving more space to those who want to vote in person, the commission states.

Drop boxes have long been used in the western states of Oregon, Washington and Colorado.

Washington state has tracked the percentage of voters who use drop boxes since 2012, and the results show an increasing reliance in the past decade. In Clark County, where hundreds of ballots were destroyed by a fire at a ballot box Monday, 60% of the ballots received are from ballot drop boxes and 40% are received by mail, Clark County Auditor Greg Kimsey said.

Since a 1998 ballot initiative, Oregon has conducted its elections by mail. Every registered voter receives a ballot several weeks before the election, and the ballots can be mailed back or delivered to a drop box. Oregon consequently had the highest voter turnout rate in the country in 2022, according to the Elections Performance Index from the Massachusetts Institute of Technology.

Best practices for securing drop boxes

Drop boxes can be either staffed or unstaffed and can be temporary or permanent structures. They are generally placed in designated public places, such as near an election office, inside a library or at a polling place, according to the US Election Assistance Commission.

The commission offers a series of recommendations for ensuring the boxes are secure.

The unstaffed, 24-hour ballot drop boxes should be made of durable material such as steel and permanently cemented into the ground, generally at a cost of about $6,000 each, the commission says. In addition, the commission recommends drop boxes have a video surveillance camera, media storage device, decal for branding and information, extra keys for access and security seals.

Only an election official or designated drop box team should have access, ideally bipartisan teams of poll workers or temporary workers to pick up the ballots on a regular basis, according to the commission.

Each state has specific rules on how to secure these drop boxes, including with locks, video feeds, chain of custody requirements, police presence and even fire suppression.

How Oregon’s most populous county secures its boxes

In Oregon, all counties are required to submit security plans to their office, the Secretary of State’s office told CNN.

In Multnomah County, Oregon’s most populous county and home to Portland, one of the drop boxes was set aflame this week. But only three out of 412 ballots inside the box were damaged, according to Elections Director Tim Scott. That’s because their drop boxes have a dry chemical fire suppressant system that activates in response to heat, similar to those seen in commercial kitchens, Scott explained.

“It worked exactly as it was supposed to,” he said. “As soon as there was heat, it discharged the contents and immediately put out the flames.”

That fire suppressant system is just one of many security factors in the county’s drop boxes.

The boxes are made by a company called Laserfab, which builds and supplies more than 1,000 boxes that they call “Vote Armor” in 15 different states, including in Multnomah County and in Washington’s two largest counties, King and Pierce.

Larry Olson, the vice president of Laserfab, told CNN they worked closely with election officials to design the ballot boxes to be as tamper-proof as possible.

For example, the slots of the boxes are small to allow in only a ballot. The tops of the boxes are slanted so rainwater flows away from ballots. Hinges are on the inside, making it hard for anyone to use a crowbar to break inside. And each box is made of steel and can weigh up to 1,000 pounds, making it sturdy enough to survive a car crash or other physical damage, according to Olson.

“It’s not something (that) somebody can just go unscrew a few bolts and grab and run away with,” Olson said.

Scott, the elections director, said there are about 15 drop boxes in Multnomah County, as well as about another 15 staffed sites where people can drop off their ballots. He said the county considers not just the construction of the boxes but also their location, preferably placing them in well-lit, high-trafficked areas for security.

“It’s important for each election jurisdiction to put a lot of thought into where they place their drop boxes, how they are messaging to voters about how to use those drop boxes, and from my perspective, for Multnomah County, I feel like all the security measures that we had in place really paid off in this incident,” Scott said.

The heated politics of drop boxes

Drop boxes became more common nationally during the 2020 election amid concerns about the Covid-19 pandemic and about the timeliness of the postal service.

According to a Pew Research Center study of the 2020 election, 41% of mail-in voters returned their ballot to a drop box, 44% returned their ballot by mail and the final 15% returned their ballot to an election official or poll worker. Overall, Biden voters were much more likely to vote by absentee or mail-in ballot than Trump voters, the study found.

Since 2020, drop boxes have become a flashpoint in America’s polarized politics, as former President Donald Trump has falsely criticized them as rife for fraud.

Their use is particularly heated in the swing state of Wisconsin, which ruled drop boxes legal in 2020, mostly banned them in 2022 but made them legal again in 2024.

Overall, 11 states have banned the use of drop boxes, and all of them went for Trump in the 2020 election, according to the Movement Advancement Project, a nonprofit think tank. Drop boxes are required or allowed and are broadly accessible in 29 states, required or allowed but limited or restricted in five states, and five states plus Washington, DC, have no law or policy, according to the non-profit.

The FBI and Department of Homeland Security recently issued a bulletin raising concerns that “election-related grievances,” such as a belief in voter fraud, could motivate domestic extremists to engage in violence in the weeks before and after the November election.

In the intelligence bulletin obtained by CNN, the agencies said some domestic violent extremists likely see publicly accessible locations, including ballot drop boxes, as “attractive targets.”