Olancha Dunes (640 acres)
Dove Springs (3000 acres)
Jawbone Canyon (5570 acres)
Spangler Hills (68,500 acres)
Dumont Dunes (2300 acres)
Silurian Dry Lake (1330 acres)
Rasor (23,680 acres)
Stoddard Valley (114,000 acres)
El Mirage (1800 acres)
Johnson Valley (250,000 acres)
Rice Valley Dunes (2600 acres)
Arroyo Salada (7700 acres)
Plaster City (41,000 acres)
Glamis (Gecko, Buttercup Valley -- 261,000 acres)
Pismo Dunes (2500 acres)
Spillway Park (247 acres)
Santa Ynez River Cycle Area (45)
Red Rock (3015 acres)
Hungry Valley (20,000 acres)
De Anza Cycle Park (659 acres)
Anza-Borrego (600,000 acres)
Heber Dunes County Park (200)
Osborne County Park (10 acres)
Ocotillo Wells SVRA (14,600)
Rowher Flats (Texas Canyon) - (10,000 acres)
Little Rock Resevoir (125 acres)
San Gabriel Canyon (150 acres)
3NO7Y (100 acres)
3NO3E (90 acres)
Corral Canyon (1200 acres)
Wildomar (360 acres)
The Great Sand Dunes in Colorado are about 150,000 acres. So yes Glamis (with gecko, buttercup) has more acrage. However, I was specifically speaking about size of dunes. Colorado has the highest dunes in North America. Star Dune rises 750 feet from its base to its crest. Unfortunately, the feds have it closely monitored and allow no motorized traffic. However, I do occasionally see the unauthorized markings of desert toys criss crossing the dunes.