Explanation: California has become the only American state. The completion of the transcontinental railroad in 1869, moreover, left the state of its isolation, and the bet to the point of agriculture was established on irrigation and on the use of cheap cheap seasonal labor quickly. California's first agricultural producer. Further, an oil discovery and exploration triggered a new influx of population, an exponential demographic growth that allowed San Francisco to become yet another large Pacific Coast city from 1890. In 1906, it was destroyed by an earthquake .
