On New York’s Upper East Side, during a recent January snowstorm, a crisp head of Iceberg lettuce was selling for $1.49 retail. This agricultural and economic miracle speaks to the efficiency and bounty of U.S. food production and improvements in American diet during the last hundred years.

The chance to eat fresh winter lettuce is historically novel. In the late nineteenth-century, lettuce was a rare luxury, grown in elaborate hothouses and sold as a delicacy to the rich, reserved for festive meals and special occasions.

Philadelphia and Boston built and farmed acres of lettuce under steel and glass. Coal-fired furnaces brought steam heat to greenhouses in the 1880s, and steam pipes were set into pits, tunnels and rows. So-named Boston leaf lettuce was grown in small pots, the root balls wrapped in waxed paper with a ribbon, not unlike hydroponic lettuce sold in markets today. Suburban Belmont’s expansive greenhouses also grew winter asparagus, tomatoes, cucumbers, and melons, sold locally and shipped by train to New York City.

With the rapid growth of the California lettuce industry, born in Los Angeles County, the era of greenhouse lettuce faded. Between 1917 and 1926, the amount of California lettuce that was shipped by rail rose fifteen-fold. Lettuce production soon moved to the Salinas Valley. The growing conditions were equal or preferable, and in Los Angeles, truck farms were being subdivided as residential real estate. Refrigeration made continental transport possible.