The first measurable increase in viticulture during the American period in San Luis Obispo County occurred in the 1880s. Charles L. Sullivan notes in A Companion to California Wine, that government records show approximately 35 grape growers planted an estimated 500 acres of vines during this period.
Most vineyards were located in two areas: near the town of San Luis Obispo and south of Paso Robles near Templeton. Zinfandel and Burger grape varietals were the major crops. A few acres of Riesling were also planted.
There were nine small wineries in San Luis Obispo County in the 1880s. The most famous was the historic Andrew York Winery west of Templeton, purchased in 1882 from Jacob Grandstaff who homesteaded the property 1875. Jacob planted a small vineyard with mission grapes.
By 1900 there were more than 1,000 acres of wine grapes in the county.