In the early 1900s. Alfred Stieglitz (1864–1946) is the acknowledged “father of modern photography.” His interest in the medium began when he was just a toddler: at the age of two, he became obsessed with a photo of his cousin, carrying it with him at all times. When he was nine years old, he took exception to a professional photographer’s practice of using pigment to color a black-and-white photo, complaining that this spoiled the quality of the print.

Between 1887 and 1911 Stieglitz worked to establish photography as a valid form of artistic expression, a pursuit for which he was sometimes publicly derided. He believed that photography should be separate from painting, but on an equal footing as an art form. He also strove to differentiate photography by instilling it with an American essence; the streets of New York City became his subject. By the time Stieglitz founded the Photo-Secession Group in 1902, he had developed a uniquely American art form. Stieglitz also published and edited photography magazines, most notably Camera Work (1903–17). After an unhappy first marriage, in 1924, Stieglitz married American artist Georgia O’Keeffe (1887–1986), who became the subject of one of his best-known series of works.