William M. Bristol, born in 1859, came to Southern California in 1882, bought an orange orchard in East Highland in 1891, married Francis "Fannie" Dearborn in 1893, and became a respected writer, poet, community leader, and promoter of the region. After attending the December 23, 1917, dedication of the Santa Fe and Salt Lake Trail Monument in Cajon Pass, he began planning Camp Cajon as a welcoming rest stop for motorists traveling the increasingly busy automobile corridor into Southern California after crossing the Mojave Desert. Built on National Old Trails Road, the first United States "Ocean to Ocean Highway," Camp Cajon opened with a grand dedication on July 4, 1919, and developed into a well-equipped auto camp with picnic, cooking, camping, and entertainment facilities. Bristol secured donations for oversized concrete picnic tables, stoves, and barbecue pits, with sponsors receiving cast-iron tablets bearing promotional inscriptions, and the table design was later copied for parks in Southern California, Michigan, and Texas. As traffic increased after National Old Trails Road became U.S. Route 66 in 1926, Camp Cajon became known nationwide as "The Gateway to Southern California," expanded to both sides of the highway with outpost buildings sponsored by organizations including the Elks Club, the Mission Inn, the Knights of Pythias, and the Santa Fe Railroad, and some facilities were moved to make room for road widening. The Great Flood of 1938 severely damaged the camp and much of the surrounding region, and because rebuilding was costly and Route 66 urgently needed widening, county and road officials closed and abandoned Camp Cajon. Some of its concrete picnic tables survived and were moved to parks in San Bernardino, while the nearby Santa Fe and Salt Lake Trail Monument, first dedicated in 1917 to honor pioneers and long-standing travel routes through Cajon Pass, was relocated several times because of road changes and later placed at this site around 1969.