The annual Riverside County Fair and Date Festival commemorates the region's date-growing industry, which began around 1900. One of the early innovators of this particular agricultural enterprise was Mr. R.H. Postlethwaite, an Englishman with a background in mining, who opened the Valley Packing Association in Coachella with his business partner, Robins Russel, in 1920. Here they packed grown locally-grown dates, as well as those imported from Iraq, and moved to El Monte in 1922, then to Monrovia in 1923, where they opened up shop at 900 S. Magnolia Avenue.
Postlethwaite, who was educated in England, spent his younger years in New Zealand, where he was co-owner of the New Zealand Engineering and Electrical Company, a business that built dredging machines and electric lighting for mines. He moved to California in 1896, where he joined Risdon Iron Works, a San Francisco firm, and designed the "Risdon Gold Dredge," which was used in mining operations in Oroville. Shortly after entering the date business, Postlethwaite designed a date-drying machine, which ran the fruit on a conveyer belt through a tunnel where it was blasted with 150-degree air currents.
Postlethwaite's career in date packing was nearly cut short, however. In February 1924, he was filling up his car with gas at a Penn Oil station on Union Street in Pasadena when the roof of the station collapsed, burying him under several tons of concrete and leaving him with a broken collar bone, crushed chest and life-threatening internal injuries. He was pulled from the rubble by several attendants, and miraculously survived the accident.
Postlethwaite was fortunate, for by the mid-1920s, the date packing business was flourishing. In 1925 alone, 750,000 pounds of dates were processed at the Valley Packing Association warehouse. According to several accounts from the era in the Los Angeles Times, a sizable portion of all dates grown in the Coachella Valley during the 1920s seem to have made their way through the Monrovia packing house, where they were dried, fumigated, packed and shipped off to various distributors around Los Angeles and other parts of the country. In 1924, the newspaper identified the facility as "one of the largest" fruit packing houses in Southern California.
Procedures at the plant were meticulous. After being carefully sorted, dried and fumigated, the dates were packed into waxed cartons lined with aluminum foil, carefully inspected, and then sealed with cellophane. Other dates were left moist and packed into jars for "fancy dessert and salad use." These jars were vacuum-sealed and sterilized with a steam heater at more than 200 degrees.
In retrospect, some of the plant's methods were also highly dangerous. In an era before the dangers of pesticides were widely known, dates were fumigated with carbon bisulphide, a substance later found to be "a neurotoxin and fetotoxin that causes thyroid and adrenal changes and heart, liver, and kidney damage," according to a 2008 book on pesticides by organic farming activist Will Allen, and which was also highly explosive.
Approximately ten different varieties of dates cycled through the Valley Packing house, but the most popular was the Deglet Noor, which originated in Algeria, and remains the dominant variety grown in the U.S. today.
R.H. Postlethwaite's wife also helped with operations at the plant, designing the glass jar packing methods, and circulating various date recipes, such as date jelly and "Waihi Cake," a New Zealand pastry.
It is unclear exactly when the packing house closed; a 1971 Date Growers Institute report claims that it operated until after WWII, but a 1938 Monrovia telephone directory shows no listing for the business. If the plant did close in the 1930s, Postlethwaite apparently remained in the date growing industry, authoring a 1938 book, The Coachella Valley and its Date Industry. His partner, Robins Russel, became general manager of the Mutual Orange Distributors packing house in Chula Vista, California.