Final answer:
The Piedmont is the region in the eastern United States between the Atlantic Coastal Plain and the Appalachian Mountains, characterized by rolling hills and small mountains.
Step-by-step explanation:
The region located in the eastern United States between the Atlantic Coastal Plain and the Appalachian Mountains, consisting of an upland and lowland section, is known as the Piedmont.
The Piedmont is an area characterized by rolling hills and small mountains, and it is composed of igneous and metamorphic rock from the cores of long-eroded mountain chains. This region lies southeast of the Blue Ridge and is considered part of the southeastern portion of the United States, extending from New Jersey to Alabama.