Rancho Arroyo Seco was a 16,523-acre (66.87 km2) Mexican land grant in the Salinas Valley, in present-day Monterey County, California. It was given in 1840 by Governor Juan B. Alvarado to Joaquín de la Torre. The grant extended along the west bank of the Salinas River at Arroyo Seco Creek, and encompassed present-day Greenfield.