"I realized I had to do it," Peterman said.
There are more than 300 blue postal service mailboxes in the city of Seattle. Last year, Peterman set out to take a selfie with each and every one.
"I would check my map and see, okay, there's some boxes along the route that I can hit," he said. "The first ones I did were in the four corners of the city. I wanted to establish those boundaries first."
Peterman discovered that the boxes make excellent models.
"Mailboxes stay put," Peterman said. "They take direction beautifully."
Every one has a story to tell.
"Some are happy, because they're all very dutiful civil servants," said Peterman.
Peterman felt bad for one little blue friend he found hanging out at Northgate.
"Mailboxes are built to be outdoors, and here's this mailbox inside. In a hallway in a mall. And it just reminded me of a caged bird," he said.
Peterman said his project isn't meant to change the world.
"It makes no political statement, no social statement."
He doesn't do it to express himself.
"Some people might consider this art. I don't know."
In fact, he said it hardly even gives him a sense of accomplishment.
"It's the most meaningless thing I've ever done."
But done it, he has, celebrating with friends and followers with one last, great selfie, as he captured mailbox #346. The grand finale of a completely meaningless adventure.
"This is Seattle, so it's certainly not the weirdest thing anyone's ever seen."