In spring 1967, Pierce made his first bid for the mayoralty of Ann Arbor, winning the Democratic nomination but losing the general election to incumbent Republican mayor Wendell E. Hulcher.
He won the Democratic nomination by defeating University of Michigan professor Bunyan Bryant, a liberal activist who was bidding to become the city's second African-American mayor, and he subsequently beat out Republican candidate Richard A. Hadler in the general election.
In 1996, Pierce co-founded the group Merian's Friends, which promoted the legalization of physician aid in dying for terminally ill patients, and served as its volunteer chairman.
The group vigorously campaigned for a 1997 Michigan ballot initiative to legalize the practice, but voters rejected the measure by a considerable margin.
Pierce died in Ann Arbor in 2002 and is survived by three daughters, Lynne, Amy and Jan, and one son, Paul.