The Big Valley was based loosely on the Hill Ranch located at the western edge of Calaveras County, not far from Stockton (one episode places the Barkley Ranch a few hours ride from town while another has Jarrod riding past a Calaveras County sign on his way to the TV series’ ranch). The Hill Ranch existed from 1855 until 1931, exceeded 1,000 acres (4.0 km2), and had the Mokelumne River running through it. Lawson Hill ran the ranch until he was murdered in 1861. His wife Euphemia (aka “Auntie Hill”) then became the matriarch. During their marriage they had four children, one daughter and three sons. Today, the location of the ranch is covered by the waters of Lake Camanche. A California State historical marker standing at Camanche South Shore Park mentions the historic ranch.