Rancho Suey was a 48,834-acre (197.62 km2) Mexican land grant in present-day southern San Luis Obispo County and northern Santa Barbara County, California given in 1837 by Governor Juan B. Alvarado to María Ramona Carrillo de Pacheco. The grant was east of present-day Santa Maria and extended along the San Luis Obispo-Santa Barbara County line, and between the Santa Maria River and the Cuyama River.