What region of the United States did Mound Builders reside in?

Eastern United States

Explanation:

Mound Builders, in North American archaeology, the name given to those people who built mounds in a large area from the Great Lakes to the Gulf of Mexico and from the Mississippi River to the Appalachian Mts. The greatest concentrations of mounds are found in the Mississippi and Ohio valleys.

if you are talking about current time the answer is no

if you are talking about when the colonies were developing the answer is yes