Estimates of the Population of Native Californians prior to and after European contact have varied substantially. Pre-contact estimates range from 133,000 to 705,000 with some recent scholars concluding that these estimates are low. Following the arrival of Europeans in California, disease and violence reduced the population to as low as 25,000. During and after the California Gold Rush, it is estimated that miners and others killed about 4,500 Indigenous people of California between 1849 and 1870. As of 2005, California is the state with the largest self-identified Native American population according to the U.S. Census at 696,600.
Historians have calculated the Native Californian population prior to European entry into the region using a number of different methods, including:
Few analysts claim that these methods yield accurate numbers. The estimates developed by different analysts commonly vary by a factor of two or more. Stephen Powers initially estimated that the pre-contact population of the state was 1,520,000. He later reduced this figure to 705,000.
C. Hart Merriam offered the first detailed analysis. He based his estimates on mission records and extrapolated that to non-missionized areas. His estimate for the state as a whole was 260,000. Alfred L. Kroeber made a detailed re-analysis, both for the state as a whole and for the individual ethnolinguistic groups within it. He reduced Merriam's figure by about half, to 133,000 Native Californians in 1770.
Martin A. Baumhoff used an ecological basis to evaluate the potential carrying capacity and estimated an aboriginal population of 350,000.
Sherburne F. Cook was the most persistent and painstaking student of the problem, examining in detail both pre-contact estimates and the history of demographic decline during mission and post-mission periods. Initially, in 1943, Cook arrived at a figure only 7% higher than the one previously suggested by Kroeber: 133,550 (excluding the Modoc, Northern Paiute, Washoe, Owens Valley Paiute, and Colorado River Yumans).:161–194 Cook later raised his estimate to 310,000.:161–194
Some scholars now believe that waves of epidemic diseases reached California well in advance of the arrival of the Franciscans in 1769. If correct, this may imply that population estimates using the beginning of the mission period as a baseline have substantially underestimated the state's pre-Columbian population.
The decline of Native Californian populations during the late 18th and 19th centuries was investigated in most detail by Cook. Cook assessed the relative importance of the various sources of the decline, including Old World epidemic diseases, violence, nutritional changes, and cultural shock. Declines tended to be steepest in the areas directly affected by the missions and the Gold Rush. Other studies have addressed the changes that occurred within individual regions or ethnolinguistic groups.
The Native Californian population reached its nadir of around 25,000 at the end of the 19th century. Based on Kroeber's estimate of 133,000 people in 1770, this represents a more than 80% decrease. Using Cook's revised figure, it constitutes a decline of more than 90%. On this Cook rendered his harshest criticism:
The first (factor) was the food supply... The second factor was disease. ...
A third factor, which strongly intensified the effect of the other two, was the social and physical disruption visited upon the Indian. He was driven from his home by the thousands, starved, beaten, raped, and murdered with impunity. He was not only given no assistance in the struggle against foreign diseases, but was prevented from adopting even the most elementary measures to secure his food, clothing, and shelter. The utter devastation caused by the white man was literally incredible, and not until the population figures are examined does the extent of the havoc become evident.:200
The population subsequently rose substantially throughout the 20th century. This recovery may represent both true demographic growth and changing patterns in ethnic self-description. In the 21st century, after more than eight generations of close interaction between Native Californians and individuals of European, Asian, African, and other Native American descent, there can be little objective basis for quantifying the Native Californian component within the state's population. However, reservation rolls and census self-descriptions provide some information.