The economy of the Southern colonies of what became the US was centered around what we call staple crops. In other words, the Southern economy was based on raising large amounts of a very few crops and selling the produce, rather than on more varied activities as was the case in the North. The Southern economy was one of plantations raising staples rather than of family farms raising nearly everything a family needed.
For example, in early Virginia, the staple crop was tobacco. Farther south, the plantations produced things like rice and indigo. The Carolinas, for example, exported 18 million pounds of rice in 1730. This was typical of the South's economy -- raising and exporting large amounts of a single crop.