In the early twenty-first century, 80 percent of the tomato crop is used in processed foods. Tomatoes were first canned in New Jersey during the 1840s, and the tomato canning industry accelerated during and after the Civil War. Cans were fashioned by hand, and the seams and bottoms were soldered on. The cans were then boiled in water. The cans were hand-filled, and the cappers soldered on the lids one at a time.
The effects of the Civil War on tomato-related industries in the North were particularly dramatic. To feed the northern army, contracts were let to canning factories, which employed mostly women. These contracts greatly stimulated the growth of tomato canneries. Confederate soldiers, who often endured meager rations, fought not only for the southern cause but also to acquire a square meal from a defeated Union Army’s supplies, which often included canned tomatoes. By the end of the war, empty tomato cans were found everywhere.