Several people tweeted pictures of locked mailboxes in the city, prompting "Burbank" to trend.
Eyewitness News reached out to the USPS for an explanation, and an employee said it's common practice for mailboxes outside post offices to be locked on days they are closed in an effort to prevent vandalism.
We noticed the mailboxes can still be accessed from the other side.
Trump admits he's blocking additional postal service funding to stop mail-in ballots
Meanwhile, the battle over mail-in ballots is escalating. House Speaker Nancy Pelosi is calling the House back into session. They're usually off for the month of August.
They are expected to vote on a bill prohibiting changes to Postal Service operations. President Donald Trump has been trying to block coronavirus relief funding from going to USPS, but the Postal Service says it needs the money to handle the anticipated surge in mail-in ballots.
The Associated Press contributed to this report.