Horton died Wednesday at a nursing home in the Sherman Oaks area of Los Angeles, where she had been recovering from a stroke, her son Vaughn Thornton said.
Horton was a teenager in the Detroit suburb of Inkster when she and friends formed a group they called "The Casinyets," short for "Can't Sing Yet."
By the time she was 15, Motown had given the group a new name and a hit song in "Please Mr. Postman." The tune, more pop-oriented than much of Motown's early recordings, was later covered by the Beatles and others.
"Gladys was a very, very special lady, and I loved the way she sang with her raspy, soulful voice," Motown founder Berry Gordy said in a statement. "We will all miss her, and she will always be a part of the Motown family."
He noted that "Please Mr. Postman" was the first No. 1 hit for the record label that would become known as Hitsville USA and produce such other popular all-girl groups as the Supremes and Vandellas.
The Marvelettes also had a hit with "Beachwood 4-5789." Their other popular songs included "Playboy," "Too Many Fish in the Sea" and "Twistin' Postman."
By the mid-1960s, however, the group's success began to wane as it was eclipsed by the Supremes and other Motown acts.
Horton was replaced as the group's lead singer in 1965, and she left the Marvelettes two years later.
Copyright © 2011 The Associated Press
