AYER -- At her own retirement party, Ann Callahan is serving other people cake.

She darts around with a plate of chocolate cake in each hand, asking who hasn't received any yet, who needs a soda and what she can do for everyone.

Callahan has made a career out of serving people, retiring this month after nearly 33 years working in Ayer town government.

Callahan worked as town clerk and tax collector from 1992 to 2010, after previously serving as treasurer's secretary and assistant tax collector. Since leaving the Town Clerk's Office in 2010, she has worked as a registrar of voters.

About 20 family members and colleagues gathered at Ayer Town Hall Wednesday night to celebrate Callahan's decades of service to the town of Ayer at her retirement party.

When asked about her own time in town government, Callahan is quiet and humble. She left because "it was time," has no plans for her retirement yet and only started working in the Town Clerk's Office because the person who worked there at the time quit.

She reflects on her time in town government by simply saying, "I always loved it here. I did everything in this office."

But others give her the praise that she won't give herself.

Ayer Town Clerk John Canney, who took over the position after Callahan left it in 2010, said Callahan worked closely with him for his first three weeks in office, helping him to learn the ins and outs of the job.

"Ann stuck right with me to help me learn how to do the job and understand what the office was about. I'm so grateful for her help," Canney said.

He emphasized Callahan's kindness and willingness to assist, which he said left an impact on all those with whom she worked.

"Her impact speaks for itself when you look around," Canney said at the party. "It's a tribute to her integrity, honesty and her love of the town of Ayer that all these people have shown up."

Poll worker Marion Smith said Callahan always put others before herself.

"Ann was a sweetheart," Smith said. "She was always easygoing, a great woman. She was totally dedicated for a lot of years."

Pauline Hamel, a former Ayer selectman, added that Callahan was so organized that she could find any information you wanted, even if it was 100 years old.

A lifelong resident of Ayer, Callahan's personal connection to the town made her a natural fit for public office.

Aline Migrants, who volunteers with Callahan as a registrar of voters, said that people like Callahan, who dedicate their lives to the service of one town, are becoming increasingly unique.

"The world has changed so much. It's part of America, part of what we were," she said. "From now on we won't know the people who serve us as intimately as we have with people like Ann. It's the end of an era."

Follow Chelsea Feinstein at Twitter.com/CEFeinstein.