The northernmost region of West Elizabeth, Big Valley is separated from Great Plains and Tall Trees by the Upper Montana River. It flows from the Owanjila Dam in the western part of Big Valley, southwards, past Tall Trees, before flowing to the east, forming the border between Great Plains and Big Valley. Hawks Eye Creek empties into the river, which then empties into Flat Iron Lake just north of Blackwater. Big Valley is also bordered by the Grizzlies West in the north and The Heartlands in the east.
Big Valley is a mountainous region covered in forests. The town of Strawberry is found within Big Valley, and serves as the "capital" of the territory. The climate of Big Valley is moderately cold, with the temperature typically being under 15 °C (59 °F) at day and sometimes below 0 °C (32 °F) during the night.
The Big Valley region seems to bear a resemblance to a number of forested areas in the western United States, particularly in California and Colorado. Big Valley's most notable inspiration is the Sierra Nevada Mountains of California. The town of Strawberry is largely based around the real-life Strawberry, California, while also sharing many similarities to Yosemite. Based on its close proximity to The Heartlands and Great Plains, it may also be based on parts of Colorado.
This is the only region in West Elizabeth which is accessible for Arthur Morgan.
Supposedly, the name of Big Valley was originally going to be "Great Valley", but the name was already taken; the 1988 film The Land Before Time had the Great Valley named as the most prominent location in the aforementioned original film and its subsequent thirteen direct-to-video sequels, the latest of which released in 2016, during Red Dead Redemption 2's development.
The name "Big Valley" is in line with the names of the two other regions of West Elizabeth (Tall Trees and Great Plains) where the names are preceded by an adjective describing the location.
The Big Valley was a Western television series that ran from 1965 to 1969. One of the show's main protagonists, Heath Barkley, was played by Lee Majors, who also played the voice of Mitch Baker in Rockstar Games's Grand Theft Auto: Vice City. The Big Valley television series itself was based on the Hill Ranch in California’s Calaveras County, whose county seat is San Andreas.