The energetic 98-year-old recently put on her uniform and was joined by a few members from Troop 1814 at a cookie sales table they set up at Phoebe Berks, the retirement community in Wernersville, Pennsylvania, where Backenstoe lives.
"I love to talk to the little girls today and tell them what I sold cookies for when I started: 15 cents!" Backenstoe told TODAY.
For Backenstoe, being a Girl Scout is a lifestyle, said Donna Schudel, community relations specialist at Phoebe Berks retirement community.
"Her mom made her wait until she was 10 and she never looked back," Schudel said. "She was a regional director, she ran camps, she took the Girl Scouts to Switzerland and Jamaica. She's a Girl Scout enthusiast."
Backenstoe even drives around her community in a souped-up golf car, complete with a Girl Scouts bumper sticker on the back.
"Ronnie is like their ambassador," said Schudel. "She's always in full uniform and smiling."
Once she started Girl Scouts, Backenstoe was hooked. When asked what she loves most about being a Girl Scout, she said it's the message of service and how the organization teaches children how to live well.
"Girl Scouts is one of the best organizations in the world," she said. "It teaches children how to live life and how to treat other people and to do service for other people who need help."
A lot has changed since Backenstoe started going to meetings and knocking on doors to sell cookies in 1932. A typical Girl Scout meeting might include learning a new cooking skill or how to can food, she said.
"Girl Scouts today are more modern," she said. "They don't just learn their way around the kitchen. They learn to build, code and continue to volunteer their time helping others."
As for those famous cookies, there were only three varieties in 1932, she recalled. There are now a dozen to chose from and can even be purchased online.
Backenstoe has been loyal to her favorite, the peanut butter Do-si-do sandwich cookies. Her late husband, Warren, who died in 2010, gave her a special nickname inspired by her favorite cookies.
"My husband used to call me the 'Peanut Butter Kid,'" she said with a laugh. "Because I love peanut butter so much!"
While she's in her 88th year as a Girl Scout, Backenstoe said she doesn't ever to plan to retire from selling cookies.
“The more you do it, the more you like it!" she said.
This story first appeared on TODAY.com. More from TODAY: