Alexa Bjornson said her son was flying solo for the first time, from Las Vegas to Oregon to see his dad.
The 7-year-old has high-functioning autism, and like many children may frequently ask, "Are we there yet?"
Bjornson said she was worried her son, Landon, might wear down his Southwest Airlines seatmate, so she sought to turn the challenge into an incentive. She wrote a note explaining her son has autism and she tucked $US10 ($A14) into the note as a thank you for whoever might help Landon feel safe and comfortable.
"I thought, 'How do I make it so whoever's sitting next to him won't look at him as a burden but more of like, I can help this kiddo get through the day,' " she told KATU.
Landon wound up next to Ben Pedraza, who said he didn't need the $10 because the two got along great. He took a photo of Landon and himself on the nonstop flight and sent a comforting message to mom Alexa.
"He did ask if we were there yet several times but he was a great travel buddy," Pedraza wrote. "We had a good time and played a few rounds of rock-paper-scissors. He's a great kid and you're a lucky mom."
Bjornson shared the note from Pedraza and a cute picture of the two seatmates on her Facebook page, and the post has received 118,000 shares. Pedraza said he took her $US10 and donated it to Autism-Society.org.
Pedraza told KATU that the grade-schooler was an easy travelling companion but after a time, Landon told Pedraza he'd had it with his brand of humour.
"We were cracking jokes, and after a while, he asked me to quit making dad jokes," he said.
Bjornson wrote in her Facebook post that she's grateful to the stranger who showed her "there are still kind people in the world who make a difference."