Arroyo Grande is a city in San Luis Obispo County, California, United States. The population was 17,252 as of the 2010 Census.
The earliest inhabitants of the Arroyo Grande Valley were Chumash Indians, who conducted extensive trade with other Native American tribes at a considerable distance.
The first Europeans to see this stretch of coast were the crew of Portuguese explorer Juan Rodríguez Cabrillo, working in the service of Spain. The Spanish Portolá expedition was the first European visit by land, passing through the area on September 4, 1769. When Mission San Luis Obispo de Tolosa was established nearby, the Portolà trail became part of the road connecting the 21 Spanish missions (today called El Camino Real). Later, agricultural activities expanded into the area. The Arroyo Grande Valley was found to have particularly fertile ground allowing a rich produce supply that continued to this day. The area was given a Spanish name that translates into multiple meanings, "Big Gulch", "Muddy Creek", "Big Ditch", Arroyo Grande was to become a prosperous and important ranch and farm community.
Francis Ziba Branch, originally from New York, saw the area on a hunting expedition during the period when California was part of Mexico.