Another book I read: Mud, Blood and Gold: San Francisco in 1849. It was an okay book, but it gave some numbers that I think paint a very clear story:
Approximate population of San Francisco in:
1845: 200
1846: 400
1848: 800 (end of Mexican-American War)
1849: 2,000 (beginning of year)
1849: 20,000 (end of year)
1860: 57,000
1880: 234,000 (silver in Nevada)
1906: 334,000
Approximate population of natives in Northern California in:
1769: 300,000 (first documented European contact)
1848: 150,000
1860: 30,000
It was pointed out to me that the word “decimation” does even begin to cover it, since that is 1 in 10 dying. This is 9 in 10. The reasons are complex, with disease and “loss of habitat” (if you could call it that) being the primary causes, but nonetheless, it is an astounding number.