Environmental impacts associated with the building industry have become of increasing importance. Materials and energy consumed during manufacture of building materials such as lumber affect a building's environmental performance. This study determined environmental impacts of manufacturing hardwood lumber in the southeastern US using the life-cycle inventory method. Primary data were collected and then weight-averaged on a per-unit basis of 1.0 m3 of planed dry lumber (600 oven-dry kg/m3) to find material flows and energy use. Cumulative allocated energy consumption for manufacturing 1.0 m3 planed dry lumber from 2.44 m3 of incoming logs was 5.86 GJ/m3 with 66% from wood fuel. Emission data produced through modeling estimated total biomass and fossil carbon dioxide production of 424 and 131 kg/m3, respectively, considering all impacts. A cubic meter of planed dry hardwood lumber stores 1.17 Mg CO2 equivalents as a final product. The amount of carbon stored in hardwood lumber exceeds fossil carbon emissions by a factor of nine. Therefore, as long as hardwood lumber and its carbon stay in products held in end uses, carbon stored will exceed fossil carbon emitted in manufacturing