The Raisin Industry: A Hundred and Fifty Years of Dried Grapes

The raisin industry in Fresno began with a drought, which is the kind of origin story the valley produces naturally.

By one common account, in the summer of eighteen seventy-three, before the raisin industry existed in any organized form, a heat wave and dry spell descended on the San Joaquin Valley during grape harvest. The fruit dried on the vine before it could be picked and processed as fresh grapes. A Fresno merchant named William Thompson, or in some accounts a grower, took the shriveled crop to San Francisco and offered it to a Spanish merchant, who recognized the dried product as a kind familiar from the Mediterranean and bought it. The transaction established that there was a market for dried San Joaquin Valley grapes. The industry followed.

The Thompson seedless grape, which became the dominant variety for the California raisin industry and which is named for a different William Thompson, a Yuba City grower who promoted the variety in the eighteen seventies, proved ideally suited to the Fresno conditions. The San Joaquin summer, with its weeks of temperatures above one hundred degrees and its low humidity, dried the grapes quickly and uniformly on paper trays laid out between the rows of vines. The physical process of making raisins in the San Joaquin Valley requires no machinery at the drying stage. You cut the clusters, lay them on the trays, and let the weather do the work. The technology is essentially unchanged from what the earliest Fresno raisin growers used.

Fresno County became, and remains, the primary raisin-producing county in the United States. At the industry's peak in the late twentieth century, the county was producing a very large share of the world's commercial raisin supply. The statistic varies by year and by what is counted in the world supply, but the concentration of production in a single California county is not in dispute.

The labor that harvests and processes the raisins has always been performed by farmworkers whose compensation and working conditions have been subjects of ongoing dispute. Harvest work in the San Joaquin Valley summer, cutting grapes in temperatures that regularly exceed one hundred and ten degrees, is among the most physically demanding agricultural labor in the country. Heat illness among harvest workers is a documented and recurring problem in the Fresno-area vineyards. State regulations on water, shade, and rest breaks for outdoor workers have been strengthened over the past two decades in response to documented heat deaths, though enforcement and compliance in the labor-intensive raisin harvest remains a subject of active advocacy.