Friday was her official retirement date, though she said she will stick around, no more than two days a week, to help new City Clerk Coty Ervin get accustomed to the job.
"Just until we feel like she doesn't need me," she said.
Canton leaders expressed their thanks to her during a work session Thursday.
"She has been an asset to me and the council members," Councilwoman Pat Tanner said. "I am going to miss you."
Mayor Gene Hobgood said the city would miss having Mrs. Threewitt around, adding that the city owed her a "debt of gratitude."
"She did an excellent job for us," he said.
Her career in city government began 26 years ago as a receptionist for the city of Woodstock under Mayor Evelyn Chambers. Within a year, she had worked herself up to the position of city clerk.
After five years with Woodstock, Canton Mayor Walton Davis hired her as the clerk for her hometown in 1989.
"I live in Canton. It is where I grew up. It is where I raised my family," she said. "I wanted to come here, to the community that I loved."
The Canton she started working for in 1989 is much different than the city she has been serving recently.
"Slow-paced is probably a good word," she said about the city when she started in 1989. The population then was just under 5,000 people. The city now is home to more than 22,000 people. "Now, we are fast paced every day."
During her time as clerk, she has worked with four mayors, including Davis, James Cannon, Cecil Pruett and Gene Hobgood. She also has worked with 20 different members of the Canton City Council.
"They have all made such a great contribution to my life," she said.
Some of the important events in the life of Canton that occurred during her tenure was the passing of the Smoke Free Air ordinance, improvements to the downtown Canton Theatre, improvements on Railroad Street, the building of Heritage Park and the building of the Hickory Log Creek Reservoir.
She always is proud of the downtown streetscapes with the hanging baskets.
"I love the way they look. That was a huge improvement," she said.
She said she is going to miss working with the mayor and city council as well as working with the citizens to solve their problems.
"I am going to miss the employees. They have become friends and part of my extended family," she added.
Among the activities she plans to take part in during her retirement are traveling and spending more time with her family.
Enjoy your much deserved retirement! You have served out county and community well. I remember you from my days as a reporter with the Tribune, you were one of those unique people that made the job a joy.
Thanks and take care,
Mitzie Parris-Swirk