Four days after the Supreme Court handed down its ruling in the case that bore her name, Edie Windsor crept down Fifth Avenue in a red convertible Ford Mustang while wearing a rainbow sash, one of three grand marshals in the 2013 New York gay pride parade.

After the decision, Ms. Windsor embraced her expanded profile, using her peculiar form of celebrity — that of a well-known plaintiff — to champion gay rights in New York and beyond. (Since the mid-1970s, when she left a position at I.B.M., she had been a full-time gay-rights activist.)

Although Ms. Windsor, who died on Tuesday at 88, helped the gay community achieve a pivotal victory with that 2013 decision, which granted federal recognition of same-sex marriages for the first time in United States history, her activism continued well into her final months of life.

The summer of 2017 was a swirl of activity for Ms. Windsor, and she maintained a pace that would have been impressive for someone half her age.