Ruth Ann Mullen Ewing, 80, who loved the Navy, history and Washington, died of sepsis Oct. 17 at her home in the Parkfairfax section of Alexandria.

Mrs. Ewing, nicknamed "the mother of Parkfairfax" for her work as a volunteer and historian of the wooded garden community, worked for the Department of the Navy for 33 years. Her optimistic personality, combined with impeccable organizational skills, made her a favorite colleague in the many offices where she worked, said her niece, Diane Mizell of Gaithersburg.

A sixth-generation Washingtonian, she lived in three of the city's four quadrants, excepting Southwest, while growing up. She graduated from Roosevelt High School in 1942 and went to work almost immediately as a senior typist in the Bureau of Ships, where she set up an indexing system for all the drawings and blueprints of ships in the fleet.

She married a naval architect whose duties included maintaining the presidential yacht Sequoia during the Johnson and Nixon administrations. Mrs. Ewing for years wanted to board the yacht, but without a naval commission or presidential invitation, she was out of luck, Mizell said. Finally, just before her ultimate illness, when the ship was rented out for private parties, she stepped aboard and took photos on the vessel.

Mrs. Ewing and her husband moved to Parkfairfax in 1950, just before then-U.S. Rep. Richard M. Nixon vacated the complex and then-Rep. Gerald R. Ford moved in. The development, now on the National Register of Historic Places, remained her home for the next 55 years.

She resigned from the Navy briefly in 1952 but was persuaded to return three months later. She became clerk stenographer for the electrical section of the ship technical branch. She later was the administrative assistant for the shipbuilding assistant to the chief of the bureau, where her job was to assign hull numbers to all the new ships in the fleet, and she worked closely with the office of the chief of naval operations' history section, which assigned names to the ships.

Her favorite project was her last. From 1967 until 1975, she kept track of the technical drawings, specifications and brochures from the shipbuilders, and all information from the equipment vendors working on the Spruance-class destroyers. She set up the technical library for the project and maintained a computerized record of the information exchange between the contractors and the Navy.

After her 1975 retirement, Mrs. Ewing volunteered at her apartment complex-turned-condominium and set up the development's library. She was named Parkfairfax's "outstanding volunteer" in 1980, and seven years later received an outstanding service award for compiling documentation on the history of the community. She was one of the unnamed contributors to James M. Goode's "Best Addresses: A Century of Washington's Distinguished Apartment Houses," published in 1988, which includes the Parkfairfax.

She also volunteered with public television station WETA, and the American Red Cross honored her for donating blood from 1942 to 1990. She was a longtime member of the National Geographic Society, the Smithsonian Institution, the John F. Kennedy Center for the Performing Arts and the Republican Party.

When her sister died, Mrs. Ewing, who never had children, took over the responsibility of parenting her four nieces and nephews.

Her husband of 27 years, William Nelson Ewing, died in 1977.