Mercer served on the City Council from 1976 to 1990, spending the last four years as the city's directly elected mayor. During his City Council tenure, the city approved Stoneridge mall, Hacienda Business Park, major retail and automotive centers along I-580 as well as several apartment complexes. He also guided the community through the budget cuts that followed the 1978 passage of Proposition 13 that slashed property taxes.
His commitment to economic growth and vitality for the city grew out of the experience of having to lay off employees and shut off half of the street lights in the city.
He spent much of his working career as a manager with Pacific Bell. After retiring, he worked in the title insurance industry and then joined ValleyCare to lead its foundation for several years before retiring for the final time.
Arrangements for services are pending.