area (sq. miles) | county count | state count | span (miles) | span center | span end 1 | span end 2 |
| 1 | 134919 | 2 | 21 | 1 | 4 | 1 | 695 | Clark-NV (36.22, 114.70) | Ventura-CA (33.22, 119.62) | San Juan-UT (38.50, 109.06) |
| 2 | 64286 | 1 | 32 | 1 | 4 | 3 | 499 | Douglas-WA (47.74, 119.44) | Clallam-WA (48.39, 124.75) | Sanders-MT (47.14, 114.19) |
| 3 | 49615 | 3 | 15 | 4 | 2 | 2 | 501 | Lake-OR (42.96, 120.78) | Trinity-CA (39.98, 123.54) | Union-OR (45.86, 117.75) |
| 4 | 27628 | 4 | 5 | 3 | 3 | 4 | 290 | Tooele-UT (40.48, 113.61) | White Pine-NV (38.68, 115.00) | Cassia-ID (42.69, 113.37) |
| 5 | 26672 | 4 | 5 | 8 | 1 | 6 | 264 | Pima-AZ (32.23, 111.07) | Pima-AZ (32.51, 113.33) | Cochise-AZ (31.33, 109.05) |
| 6 | 8522 | 6 | 3 | 8 | 1 | 5 | 274 | Maui-HI (20.54, 156.54) | Honolulu-HI (21.60, 158.33) | Hawaii-HI (19.45, 154.77) |
| 7 | 7525 | 9 | 2 | 4 | 2 | 7 | 229 | Lassen-CA (40.51, 120.29) | Nevada-CA (39.01, 121.22) | Washoe-NV (41.99, 119.32) |
| 8 | 7177 | 9 | 2 | 8 | 1 | 8 | 148 | Custer-ID (44.02, 114.03) | Custer-ID (44.74, 115.14) | Butte-ID (43.28, 112.95) |
| 9 | 4158 | 6 | 3 | 4 | 2 | 9 | 123 | Taos-NM (36.89, 105.74) | Alamosa-CO (37.75, 106.04) | Taos-NM (36.01, 105.53) |
| 10 | 3497 | 13 | 1 | 8 | 1 | 10 | 116 | Lewis and Clark-MT (47.25, 112.35) | Lewis and Clark-MT (46.57, 111.63) | Lewis and Clark-MT (47.92, 113.08) |
| 11 | 2966 | 13 | 1 | 8 | 1 | 13 | 78 | Luna-NM (32.19, 107.75) | Luna-NM (31.78, 108.21) | Luna-NM (32.61, 107.30) |
| 12 | 2130 | 13 | 1 | 8 | 1 | 14 | 67 | El Paso-CO (38.83, 104.54) | El Paso-CO (38.52, 104.05) | El Paso-CO (39.13, 105.03) |
| 13 | 2029 | 9 | 2 | 4 | 2 | 12 | 78 | Wahkiakum-WA (46.29, 123.73) | Pacific-WA (46.79, 124.10) | Clatsop-OR (45.78, 123.36) |
| 14 | 1593 | 9 | 2 | 8 | 1 | 16 | 55 | Columbia-WA (46.35, 117.76) | Columbia-WA (46.00, 118.00) | Garfield-WA (46.70, 117.47) |
| 15 | 1400 | 6 | 3 | 8 | 1 | 11 | 79 | Summit-CO (39.44, 106.03) | Lake-CO (39.06, 106.58) | Clear Creek-CO (39.75, 105.40) |
| 16 | 1124 | 13 | 1 | 8 | 1 | 15 | 56 | Hinsdale-CO (37.80, 107.29) | Hinsdale-CO (38.15, 107.00) | Hinsdale-CO (37.42, 107.48) |
| 17 | 803 | 13 | 1 | 8 | 1 | 17 | 50 | Contra Costa-CA (37.93, 121.98) | Contra Costa-CA (37.85, 121.53) | Contra Costa-CA (37.97, 122.44) |
| 18 | 446 | 13 | 1 | 8 | 1 | 18 | 45 | Santa Cruz-CA (37.04, 121.95) | Santa Cruz-CA (36.90, 121.59) | Santa Cruz-CA (37.19, 122.32) |