The 23-year-old, capped twice for the United States national side, is currently at the Britannia Stadium taking in a stint with the Potters.
He will then head to Merseyside on December 10th to train with Everton for a second successive year after spending time with the Toffees last winter.
Johnson is relishing his time at Stoke, where he has been catching up with international team-mates Maurice Edu and Geoff Cameron.
He told Chicago Fire's official website: "I've hung out with both of them. I'm actually staying with Maurice at the moment.
"They're great guys to be around and it's just good to see familiar faces and make most of the time you have with your friends while you're over here."
He added: "Training with their goalkeeper coach and getting the chance to play and train with the guys at the top level. Just seeing how another team operates gives you perspective."
"I think it's been a great experience working with guys like Thomas Sorensen, Asmir Begovic and Carlo Nash."
Johnson is looking forward to linking up with USA No.1 Tim Howard and goalkeeping coach Chris Woods again at Everton.
"Having been in with the national team a lot more this past year, training with Chris and Tim again here is a fantastic opportunity to keep some continuity and show how I'm growing," he said.
"To be in that environment day-in and day-out and make yourself a better goalkeeper will do wonders for me as a player."
Don't miss any live and exclusive football coverage this festive season. Click here to visit Sky Sports' Festive Calendar