Georgia O'Keeffe's 1917 New York exhibition venue was the gallery known as 291.
The gallery was named for its address at 291 Fifth Avenue in Manhattan. Alfred Stieglitz operated it and used the space to exhibit European modernists as well as innovative American artists. Its earlier formal name was the Little Galleries of the Photo-Secession.
O'Keeffe's first solo exhibition opened there in April 1917. The show included charcoal drawings and watercolors made while she was developing an abstract visual language. Stieglitz's promotion of the work helped bring her to the attention of New York's art community.
The gallery closed in 1917, but Stieglitz continued presenting O'Keeffe's work at later galleries. The number 291 is therefore a venue name and street address, not a year or an artwork title.