Subregions- Arizona
 - Bakersfield urban area, California
- Central California
- Channel Islands region, California
- Crater Lake area, Oregon
- Craters of the Moon area, Idaho
- Fresno urban area, California
- Greater Los Angeles area, California
- Gulf of Santa Catalina, California
- Lassen Peak area, California
- Las Vegas urban area, Nevada
- Long Valley area, California
- Medicine Lake area, California
- Mexicali-Calexico urban area, California
- Mexicali urban area, Baja California, Mexico
- Monterey Bay, California
- Mount Bachelor area, Oregon
- Mount Hood area, Oregon
- Mount Jefferson area, Oregon
- Mount McLoughlin area, Oregon
- Mount Shasta area, California
- Mount Washington-Belknap Crater area, Oregon
- Nevada
- Newberry Caldera area, Oregon
- Northern California
- northern Idaho
- offshore Central California
- offshore Northern California
- offshore Oregon
- off the coast of California
- off the coast of Northern California
- off the coast of Oregon
- Oregon
- Phoenix urban area, Arizona
- Sacramento urban area, California
- San Clemente Island, Channel Islands, California
- San Diego County urban area, California
- San Francisco Bay area, California
- San Francisco Bay, California
- San Miguel Island, Channel Islands, California
- San Nicolas Island, Channel Islands, California
- San Pablo Bay, California
- San Pedro Channel, California
- Santa Barbara Channel, California
- Santa Catalina Island, Channel Islands, California
- Santa Cruz Island, Channel Islands, California
- Santa Monica Bay, California
- Santa Rosa Island, Channel Islands, California
- Southern California
- southern Idaho
- Stockton urban area, California
- Sunset Crater area, Arizona
- Three Sisters area, Oregon
- Tijuana urban area, Baja California, Mexico
- Tucson urban area, Arizona
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