Nicasio is a contiguous area of unincorporated land in west Marin County , California . The Nicasio region encompasses approximately 25,000 acres (100 kmﾲ) and has no legally defined political boundaries. Geographically it is a hydrologic zone containing the four main drainages of Nicasio Creek up to the ridgelines defining their basin. This includes: the south fork of Nicasio Creek extending from Moon Hill, along the ridge separating Nicasio from San Geronimo and Samuel P. Taylor Parks , and extending northwest towards the northern end of Platform Bridge Road; the east fork of Nicasio Creek extending from Loma Alta and the ridge on the north side of Sir Francis Drake Boulevard , extending up through Big Rock and up towards Big-Rock Ridge; the Halleck Creek drainage, up to the ridges separating Nicasio from Lucas Valley and Novato ; the northern drainages extending along the ridgelines of Rocky Ridge, Hicks Mountain and Black Mountain . A major landmark in the area is the man-made Nicasio Reservoir . Nicasio is scenically very attractive with forested and open ridgelines surrounding a wide rolling valley. The area along Lucas Valley Road follows a narrow valley with mostly forested hillsides above it. Oak, bay, and fir trees are common in the area, and along some of the creeks stands of redwoods are still found. Wildlife is abundant. Three main roads cross the area: Lucas Valley Road, Nicasio Valley Road, and the Point Reyes-Petaluma Road. Important pieces of public land in the surrounding area include Point Reyes National Seashore , portions of the Golden Gate National Recreation Area , and Samuel P. Taylor State Park . Within the Nicasio area are about 250 homes located on approximately 350 parcels. Much of the land is still used for agricultural purposes including beef and dairy cattle grazing, small-scale truck farming (including organic farming), and the raising of forage. Several small vineyards have also been recently established. The most significant non-agricultural business within Nicasio is George Lucas  Skywalker Ranch , a part of Lucasfilm Ltd., where computer generated visual effects are developed. Population estimates for the area range from about 600 to about 900 people. According to a 2004 Forbes Magazine real estate survey, Nicasio is the 23rd most expensive zip code in the US. Centrally located in this area is the small village of Nicasio itself. The town center has a post office (zip code 94946), a general store, a tiny real estate office, St. Marys Church (established in 1890), a baseball field located in the town square, Rancho Nicasio, which is a bar/restaurant/live music establishment, a Druid's Hall, as well as a number of private homes. Next to Rancho Nicasio is an organic farm, AllStar Organics , owned and operated by Janet Brown and Marty Jacobson; Janet is the vice-president of Marin Organic , Marin County's non-profit organic association. The town was founded in the early 19th century to support local agricultural, timber, and fishing activities. The town once boasted the twenty-two room Hotel Nicasio, which opened in 1867 and burned down in December 1940. Just north of town on Nicasio Valley Road is a beautiful red-painted one-room schoolhouse that opened in 1871. The building is currently a listed historical landmark. Nicasio was home of Jerry Garcia , guitarist forateful Dead , at time of his death in August 1995.