Constance Mercer, an interior designer who worked in the Washington area for more than six decades, died Oct. 17 at MedStar Georgetown University Hospital in the District. She was 80.

The cause was a stroke, said her executor, Kenneth Garrison.

Ms. Mercer began her career at W&J Sloane, the Washington furniture retailer, before moving to John Robert Interiors, where she worked for nearly two decades.

She became president of Jeffrey Associates before opening a District-based interior design firm, Mercer Associates, in 1986. Ms. Mercer had clients across the country and in Washington, where she lived, and continued working until her death.

Constance Mercer was born in Richmond, moved to the District as a girl and graduated from the old National Art School in Washington in 1952.

She held leadership positions with professional organizations including the American Society of Interior Designers, which awarded her several honors, and was inducted into the Washington Design Center’s hall of fame, said Garrison. He also said that Ms. Mercer did volunteer work with and served on the board of directors of the Washington Animal Rescue League.

She had no immediate survivors.

— Emily Langer