Rancho Punta de Quentin was a 8,877-acre (35.92 km2) Mexican land grant in present-day Marin County, California, given in 1840 by Governor Juan B. Alvarado to John B.R. Cooper.[1] The grant comprised not only the San Quentin peninsula, but also present-day Ross, Kentfield and part of San Anselmo.[2][3][4]