“I” is for Iodine. The chemical element iodine is relatively rare. It occurs naturally as a trace element in certain soils, rocks, seawater, plants and animals. In humans, it is largely found in the thyroid gland, which secretes iodine-bearing hormones responsible for regulating metabolism. A deficiency of iodine causes an unsightly swelling of the neck and jaw known as goiter. In the late 1920s the South Carolina Natural Resources Commission began a public relations campaign to advertise the high iodine levels found in fruits and vegetables grown in the state. The campaign placed the motto “Iodine” on South Carolina automobile license plates in 1930 and then expanded the phrase in subsequent years to “The Iodine State.” Columbia radio station WIS took its call letters to promote the “Wonderful Iodine State.”