Mole Hill is one of the youngest volcanoes in the Eastern United States, and is probably the last active volcano on the Eastern seaboard. It was last active 47 million years ago. It is one of two volcanoes in the Commonwealth of Virginia. (Tthe other is Trimble Knob in Monterey, Virginia.) 

Classifying a volcano as dormant or extinct is a subjective and inexact exercise. Mole Hill is most likely extinct but could be considered long dormant.

Whether or not inactive volcanoes are considered truly extinct, or just dormant, depends partly on the average repose interval between eruptions. As noted in eruptive variability, explosive eruptions like those at Toba and Yellowstone have repose intervals of hundreds of thousands of years, whereas non-explosive eruptions have very short repose intervals. Thus, the Yellowstone region, which has not experienced an eruption for 70,000 years, can not be considered extinct. In fact, many scientists consider Yellowstone to be active because of high uplift rates, frequent earthquakes, and a very active geothermal system. Many inactive scoria cones, on the other hand, may be viewed as extinct shortly after they erupt, because such volcanoes are typically monogenetic and only erupt once.