"Worthington Whittredge's Western landscapes were executed over an eleven year span beginning in 1866, when the artist made his first excursion with General John Pope's expedition to the eastern portion of the Rocky Mountains and New Mexico. The Western landscape stirred his imagination and he developed numerous on-the-spot sketches of scenes he encountered throughout his travels. As he stated in his autobiography: 'I had never seen the plains or anything like them. They impress me deeply. I cared for them more than for the mountains, and very few of my Western pictures have been produced from sketches made in the mountains, but rather from those made on the plains at that period, notwithstanding its herd of buffalo and flocks of antelope, its wild horses, deer and fleet rabbits, could hardly fail to be impressed with its vastness and silence and the appearance everywhere of innocent, primitive existence.'" (J.I.H. Baur, ed., "The Autobiography of Worthington Whittredge," Brooklyn Museum Journal , vol. I, 1942, p. 45)
The summer of intense sketching out West in 1866 would have a profound effect on the formation of Whittredge's mature style. Once back in his studio in New York, Whittredge would rework his sketches made in the field to create larger, more finished canvases. In the painting Twilight on the Plains "he not only imposed a sunset atmosphere, but also reworked the foreground, enlarging the sweep of the river, while making several adjustments to the background." (A. Janson, Worthington Whittredge, New York, 1989, p.107) Whittredge developed a particular pastoral vision while traveling in the West, relying on the careful rendering of light and color to create his spectacular images of the Western landscape.