Harvard University
Harvard Univ.: Immigration to Us, 1789 1930: California Gold Rush (1848 1858)
Describes the California Gold Rush and the impact it had on immigration to the United States and to the future demographics of California. Includes a high-resolution map of the gold region of California in 1851.
Sacramento Bee
The Sacramento Bee: Polk Is Caught in the Rush
This site discusses James K. Polk's place in the gold rush of California in the 1840's.