The National Trust for Historic Preservation started a week-long celebration of preservation in 1973 to promote historic places and heritage tourism, and demonstrate the social and economic benefits of historic preservation. It was extended to the full month of May in 2005. SoCal Landmarks featured historic landmarks in its online posts on each day in May, 2023, in support of that celebration. A portion of the proceeds from this book will be donated to local organizations working to protect and preserve historical landmarks in Southern California. SoCal Landmarks is an ongoing project to document the myriad sites, buildings, structures, monuments, and other natural and historical points of interest and/or importance that are considered locally, regionally and/or nationally as landmarks in the ten counties - Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Ventura, Kern and San Luis Obispo - stretching from the Colorado River to the Pacific Ocean and from the Mexican border to 35° 47' 28" North latitude, the northern border of San Luis Obispo, Kern, and San Bernardino counties.