John B.R. Cooper arrived in California in the early 19th century as a New England merchant mariner and settled permanently, becoming a naturalized Mexican citizen. This was a common path for Americans seeking land in California before the Mexican-American War: adopt Mexican citizenship, receive a land grant, and establish a rancho. Cooper received his grant in 1840 and used the land for cattle ranching, the dominant economic activity of the era. The grant's boundaries encompassed some of the most desirable terrain in Marin County, from the waterfront at San Quentin Point to the wooded valleys inland.

After the Mexican-American War transferred California to the United States, the land grant system collapsed, and rancho lands were divided, sold, and repurposed. The San Quentin peninsula, jutting into San Francisco Bay at the county's southeastern corner, was selected as the site for California's first state prison in 1852. San Quentin State Prison has operated continuously since then, housing some of California's most notorious inmates and becoming one of the most recognized prisons in the world. The choice of location was practical -- the peninsula was isolated and surrounded by water on three sides -- but it also meant that the rancho's most distinctive geographic feature would be forever associated with incarceration.

Beyond the prison, Rancho Punta de Quentin's lands became some of Marin County's most affluent communities. Ross, Kentfield, San Anselmo, and Larkspur developed as residential towns during the late 19th and early 20th centuries, attracting families drawn by the mild climate, proximity to San Francisco via ferry, and the natural beauty of the wooded valleys that Cooper once used for grazing cattle. The contrast between these communities and the prison that shares their rancho heritage is stark. The same land grant that produced California's most infamous penal institution also produced some of its most desirable addresses.