The Oscar winner also took to Instagram on Friday to ask fans to send in videos of anything that inspires them, whether it be "the sunrise, the sunset, something crazy, something epic, something beautiful, something weird. But just send in something."
The band also shared a video and letter on their website, telling their fans how they can contribute and to "be as brave, bold and creative as possible" when submitting their clips.
"Our goal is to create this portrait based on footage captured on a single day - July 4th, 2017 - but if there are events that transpire or images we feel we need to tell our story, we will include those," the band wrote. "Thank you for joining us on this incredible and amazing adventure, we can’t wait to see America through your eyes."
ET recently spoke with Leto at the premiere of HBO's new documentary series, The Defiant Ones, where he gushed about Wonder Woman and how the Thirty Seconds to Mars crew went to watch the film.
"I saw the film. I loved it. I thought it was incredible. They did such a good job," he shared. "I watched Wonder Woman as a kid, and I really enjoyed it."
For more on Leto's upcoming projects, watch below.