The western part of the county is defined by the course of several rivers and the irregular boundaries of adjoining counties. When the county was created, the founders wanted to include access to the transcontinental railroad, so a rectangular section was added that includes the railroad town of Truckee. What is remarkable about this is that the final shape of the county closely resembles the Deringer pocket pistol, a favorite at the time of the more urbane residents of this gold rush county.