Final answer:
Spanish and Mexican eras in California were marked by sparse land grants and ranchos establishment, which changed drastically after Mexican rule when land was given extensively to political allies. American settlers' increasing presence and the discovery of gold led to California becoming a U.S. state, accompanied by social and racial tensions.
Step-by-step explanation:
During the period of Spanish and Mexican control over California, various factors influenced the settlement and political dynamics of the region. Under Spanish rule, land grants were made to encourage settlement, but they were limited in number. The transition to Mexican governance saw a significant increase in the size and number of land grants, often given to political allies, friends, and family, which led to the proliferation of large ranchos across California. These grants were a part of a land tenure system that, post the Mexican-American War, frequently left many original landholders dispossessed of their estates.
As American interests turned westward, Manifest Destiny and geopolitical tensions spurred the increased presence of American settlers and traders in California. The Mexican government's instability in the territory led to a series of revolts and ultimately contributed to the short-lived California Republic, which was ended by John C. Fremont and American forces. Rebellions and various military strategies played a role in the evolution of political control that eventually shifted from Mexican governors and the ranchero elite to American rule.
The discovery of gold in 1848 brought a massive influx of people from various backgrounds, known as the Forty-Niners, transforming California socially, economically, and demographically. This immediate increase in population was instrumental in California's rapid admission as a U.S. state. Nonetheless, settlement and expansion were not without their darker sides, as racial tensions and discriminatory policies emerged against native populations and Mexican residents.