Prescott was named in 1881 after C.H. Prescott, the general superintendent of the Oregon Railway and Navigation company after he designated it the location for the railway’s division shops. The town was platted May 12, 1882 by the Oregon Improvement Co. In 1883 the Great Northern Pacific flour mills, built by H. P. Isaacs came in. Prescott was officially incorporated on March 13, 1903. Captain John Mullan, built the historic Mullan Road from Walla Walla to Fort Benton, Montana from 1858-1862. A portion of the road runs along the current State Road 125 from Walla Walla to near Prescott. A memorial there commemorates the event.