A smudge pot is an oil-burning device used to prevent frost on fruit trees. Generally a smudge pot has a large round base with a chimney coming out of the middle of the base. Growers used to place smudge pots between trees in an orchard; the heat and smoke from the burning oil kept the air just warm enough to prevent frost from forming on the trees. Growing citrus is a very big part of California’s agricultural economy. The Spanish missionaries who founded the missions in California were some of the ﬁrst people to grow citrus in the state. With the growth in population during the Gold Rush, commercial citrus production also grew, to supply the miners with fresh oranges. Citrus production boomed with the introduction of refrigerated railroad cars in the 1880s, allowing the state’s fruit products to be marketed throughout the nation.