This map depicts the bedrock and surficial geology of the Trigo Pass 7 ½’ quadrangle in the Trigo and southern Dome Rock Mountains in the lower Colorado River Valley, La Paz County, southwestern Arizona. The entire quadrangle is on the Yuma Proving Ground, administered by the U.S. Army, which granted us access to the area. However, the southeastern part of the quadrangle covers a restricted part of the YPG where escorts are generally required for field mapping. In this part of the quadrangle, surficial deposits were mapped using orthophotography and topography, and were not field-checked. The geologic mapping is part of a multi-year AZGS effort to map the bedrock and basin geology in the lower Colorado River Valley (e.g., Gootee et al., 2016; Johnson et al., 2017; Ferguson et al., 2018). This geologic map complements 7 previous Arizona Geological Survey 7 ½’ quadrangle mapping projects in this general area, and the geologic map of the Cunningham Mountain 7 ½’ quadrangle immediately to the north (Johnson et al., 2021).