The main purpose of this legislation is to expand the boundaries of Joshua Tree National Park in California and to honor the late Senator Dianne Feinstein by renaming the Cottonwood Visitor Center in her memory. The bill aims to enhance the park's size and accessibility while recognizing Feinstein's contributions to conservation efforts. Key provisions of the legislation include the expansion of Joshua Tree National Park by approximately 20,149 acres, as specified in a detailed map.