North Carolina is divided geographically into three regions: the coastal plain, the piedmont plateau, and the mountains. The soil of these regions varies and requires different gardening techniques.
The coastal plain has a grey sandy soil called Portsmouth sand. It’s very porous and drains fast. It usually needs amendments rich in organic matter such as compost or peat moss to absorb and hold water and add nutrients.
The piedmont plateau is a red clay base with a thin layer of organic matter. Its called Cecil soil. The clay blocks water movement and storage and plant roots are shallow. The challenge in gardening here is to add enough organic matter or sand to improve drainage and to create a deep enough layer of permeable soil for good root developement.
The mountains have a rock base on the slopes while the valleys and pockets have a rocky organic mix. The challenge is not only finding a flat location to garden but also soil deep enough to allow roots to grow.
Below is a map of North Carolina’s regions. You can find information about your state’s soil through your local agricultural extension or agricultural college. Most states also have a department of agriculture, too.
http://ncpedia.org/sites/default/files/physical_regionsm
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Arthur in the Garden! 
This reminds me of how lucky we are in the midwest with our deep, loamy soil. Not that we treat it with much respect.
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It is amazing how two places a short distance apart can have dramatically different soil. I am on the top of a hill: heavy clay soil with some organic soil, lots of rock, and about 12 inches down: nearly impenetratable yellow clay till. Two miles away in a river valley: still rocky, but very deep soil with no hard pan. Entirely different growing conditions!
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My yard is on a slope and within 100 feet the top of the slope is about 18 inches of top soil then a clay base, where as, the bottom of the slope is only about an inch of top soil before you strike clay.
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