By JANE LaTOUR

On March 25 — exactly 92 years after the Triangle Shirtwaist Co. fire of 1911 killed 146 women in 15 minutes — its infamous Greenwich Village site achieved New York City landmark status.

Mayor Michael R. Bloomberg and Landmarks Preservation Commission Chair Robert B. Tierney presided over the ceremony at the building, where management had locked the exit doors to keep the young immigrant women at their sewing machines.

For Gale Harris, Landmarks Preservationist and a member of Civil Service Technical Guild Local 375, the event held special significance. With her background in early 20th century architecture and her strong interest in labor and women’s history, Ms. Harris was the perfect person to research the history of the building and America’s worst factory fire in preparation for its landmark designation.

To begin the process, the Landmarks Commission held public hearings in November, gathering testimony from historians on the importance of preserving the site. Laura Hansen of the Municipal Art Society pointed out that “the building tells the story in a way that no other medium can. The place where history happened allows us to imagine the experience of that history, and so heightens our understanding of the past.”

Ms. Harris then began to research the history of the building. She carried out the detailed detective work in places like the Municipal Archives and the Office of the County Clerk, used New York University’s Tamiment Institute Library, and got help from DC 37 Librarian Ken Nash, who provided books on the fire and the garment industry of a century ago.

For two months, Ms. Harris compiled all of the sources to provide a complete history of the building, the industry — the city’s largest at that time — the Shirtwaistmakers’ Strike of 1909, the Triangle Fire, and the organizing that took place in the aftermath of the fire, when, “the tragedy that stunned the nation became a catalyst for a broad range of reforms.”

Her report concludes with the designation of the historic site as a landmark. Now, a new brass plaque marks the building on the corner of Washington Place and Greene Street — just off Washington Square Park. Passers-by can stop to read it and consider the tragedy that took the lives of so many working women, many of them only 14 years old. Gale Harris says she feels a special sense of satisfaction that this building — so significant in labor and women’s history — is now a city landmark. “It’s so important that due recognition has been given to this event in the history of working people.”