Of all the fashion trends set by First Lady Jackie Kennedy, she will be remembered most for her trademark pillbox hat.

It was called a pillbox hat because it looked as if it was designed to hold pills. While Mrs. Kennedy is credited with bringing the hat to the masses, the hat had existed in different forms since the 1930s. In fact, Mrs. Kennedy was not even the first “First Lady” to wear one, as the First Lady of Mexico preceded her by a year or so.

By 1963, interest in wearing the pillbox hat had already begun to fade but came to a sudden halt when Mrs. Kennedy, wearing a pink pillbox hat, cradled the President’s head in her lap after he was struck down by assassin’s bullets.