This shows the populations of California, Arizona, Nevada, Utah, and New Mexico.
Some territories covered other states. They are counted under what they share their name with.
| Year | California | Arizona | N. Mexico | Nevada | Utah |
| 1846 | 15000 | | | | |
| 1850 | 92597 | | 61547 | | 11380 |
| 1860 | 379994 | | 93514 | 6848 | 40273 |
| 1870 | 560247 | 9658 | 91874 | 42941 | 86336 |
| 1880 | 864694 | 40440 | 119565 | 62266 | 146608 |
| 1890 | 1213398 | 88243 | 160282 | 47355 | 210779 |
| 1900 | 1485053 | 122931 | 195310 | 42335 | 276749 |
| 1910 | 2377549 | 204354 | 327301 | 81875 | 373351 |
| 1920 | 3426861 | 334162 | 360350 | 77407 | 449396 |
| 1930 | 5677251 | 435573 | 423317 | 91058 | 507847 |
| 1940 | 6907387 | 499261 | 531818 | 110247 | 550310 |
| 1950 | 10586223 | 749587 | 681187 | 160083 | 688862 |
| 1960 | 15717204 | 1302161 | 951023 | 285278 | 890627 |
| 1970 | 19953134 | 1745944 | 1017055 | 488738 | 1059273 |
| 1980 | 23667902 | 2718215 | 1302894 | 800493 | 1461037 |
| 1990 | 29760021 | 3665228 | 1515069 | 1201833 | 1722850 |
| 2000 | 33871648 | 5130632 | 1819046 | 1998257 | 2233169 |
| 2010 | 37253956 | 6392017 | 2059179 | 2700551 | 2763885 |
| 2020 | 39538223 | 7151502 | 2117522 | 3104614 | 3271616 |
| 2022 | 39029342 | 7359197 | 2113344 | 3177772 | 3380800 |
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