Seventy-four new heat flow values have been determined at sites from New Jersey to Georgia, mostly in the Piedmont and Atlantic Coastal Plain provinces. Relatively high heat flows are characteristic of premetamorphic and postmetamorphic granites exposed in the Piedmont and occurring in the basement beneath the sediments of the Atlantic Coastal Plain. The Piedmont heat flow and heat generation values, determined in granites, metagranites, and one Slate Belt site, lie in a belt approximately parallel to major structural trends in the Appalachians. These values fall on or near the regression line: q(mW/m2)=29.8¿1.5(mW/2) +7.8(km)¿0.475 A(μW/m3)(R=0.97477). It is proposed that the occurrence of a thrust fault that truncates granites at a depth, D, of 7.8 km is directly responsible for this linear relation in the eastern Piedmont. Basement core from beneath the sediments of the Atlantic Coastal Plain was recovered at ten sites. Results from five of these sites plus one site in the Baltimore Gabbro define a second linear relation with a slope (D=8.0¿0.380 km; R=0.99550) approximately parallel to the Piedmont relation, but with an intercept of 48.2¿0.8 mW/m2. These two relations may represent different heat flow provinces in the southeastern United States or the linear relations may simply be a consequence of differences in the thicknesses of the upper heat-producing layer at least at far east as postmetamorphic granites sampled under the Coastal Plain.