Georgia O'Keeffe first exhibited with Alfred Stieglitz at the New York gallery known as 291.
The gallery was located at 291 Fifth Avenue in Manhattan and was formally associated with Stieglitz's pioneering presentation of modern art. In 1916, Stieglitz displayed a group of O'Keeffe's abstract charcoal drawings there after Anita Pollitzer had shown them to him.
The venue helped introduce O'Keeffe to New York's modern-art circles and became an important early stage in her public career. Stieglitz later organized further exhibitions of her work and became her husband in 1924.
The number refers to the gallery's street address, not to an exhibition title or an artwork catalog number. The gallery itself was also called the Little Galleries of the Photo-Secession before it became widely known simply as 291.