Death Valley and Joshua Tree were national monuments before becoming National Parks.

San Gabriel Mountains National Monument (20 minutes from LA downtown). If you don’t think there has ever or would ever be development pressure in this area you must not have much experience with Southern California.

I’ve been to the Sand to Snow National Monument multiple times before the designation. It is made up of several popular reserves that dot the surrounding area North of Palm Springs.

Sand to Snow National Monument is 20 minutes drive from Palm Springs. Its not THAT remote. Development in the exterior boundaries of the park were certainly one concern.