From Florida to New York and Pennsylvania dog owners have been dressing their pets in canine papal outfits with the hashtag #popedog on Instagram.
"Everyone loves cute puppies, and everyone loves Pope Francis," said John Scorr from Brooklyn, who dressed three-year-old Puggle Giles in full papal regalia (minus the staff).
"In America, we like combining the things we love.
"Giles wanted to show his support for a more progressive pontiff. Also, I suspect the Holy Father himself would find it funny."
Melissa Joy, who photographed Colin and Erica Cissne's dog Babs, in Philadelphia said: "It's very festive, and embracing of a huge event that's happening in our city."
Asked if the Pope was aware of the trend, a Vatican spokeswoman said: "I don't know if he's conscious of that. I imagine he has more important things to think about."
Dressing dogs as popes may not be a new phenomenon, however.
The Twitter account PopeDog was set up in 2013 as "a bit of fun", apparently inspired by a video of Pope costumes being made for dogs in Germany that was posted online in 2008.
Remarking on the latest craze, 'PopeDog' who owns three dogs and works in IT in the British town of Swindon said: "The US have always been crazy bonkers for dressing up their dogs, and the Pope's outfits are crying out for some canine fashion pimping - it's a collision of awesome."
Pope Francis's visit to the United States has been marked in an unexpected way by some Americans.