Major Thomas Leander (Lee) Moorhouse is most well known for being the Indian agent for the Umatilla Indian Reservation from 1889 to 1891. He was born in Marion County, Iowa on February 28, 1850. In 1861, his family moved to Walla Walla, Washington via the Oregon Trail. In his first year in the Pacific Northwest, Moorhouse stayed with family friends in the Pendleton area. Moorhouse also attended Whitman College Seminary in 1866.

Throughout his life, he worked in many different positions, including as a surveyor, businessman, and insurance salesman. During the Bannock War, he served as the governor’s field secretary, and later attained the rank of “Major” for serving as the Assistant Adjutant General of the Third Brigade of the Oregon State Militia from 1879 to 1883.

In the later years of his life, Moorhouse became an avid photographer and began taking photographs around 1897. Though the film camera was commercially available and popular in American households at the time, he opted to use professional photography techniques and materials, such as glass plates and a large camera on a tripod. Although Moorhouse considered himself an amateur photographer throughout the nearly twenty years during which he was taking photos, his photographs of Native Americans were exhibited and recognized both regionally and even nationally. Many of Moorhouse’s photographs depict eastern Oregon landscapes, small-town life, agricultural scenes, railroad and steamboat activity, and artistic portraits. He also took particular interest in documenting life on the Umatilla Indian Reservation, believing that indigenous ways of life would soon disappear entirely.

On June 1, 1926, Moorhouse passed away due to illness at the age of 76. In total, he took over eight thousand glass plate images during his life.

One of his daughters sold around three hundred images of Native American subjects to the Bureau of American Ethnology in 1935; those glass plate negatives are now housed in the National Anthropological Archives of the Smithsonian Institution. In 1949, the University of Oregon was deeded the bulk of his collection, approximately 6,500 images, many of which depict the Umatilla Indian Reservation and the Pendleton Round-Up.

The remaining 1,541 glass plate negatives were gifted to the Umatilla County Library in 1958, and then transferred to the Umatilla County Historical Society in 1987. In 2025, these images were processed and digitized with support from the Roundhouse Foundation and Whitman College and Northwest Archives.