Americans arrive, clash with Mexicans, and establish the short-lived Bear Flag Republic. The United States declares war against Mexico. The Gold Rush Mexico cedes California to the United States. The gold discovery brings people from many countries. American citizens cross the plains, sail around the Horn and cross the Isthmus.
Immigrants arrive from China, and are barred from the mines.
African-Americans come to the mines, some leave California for British Columbia. Steamboats fill the rivers. The Port of San Francisco becomes notorious for shanghaiing sailors. The Indian population shrinks. The Southern Pacific monopolizes rail traffic to and from California.