This paper develops structural dynamic methods to project future carbon fluxes in forests. These methods account for land management changes on both the intensive and extensive margins, both of which are critical components of future carbon fluxes. When implemented, the model suggests that U.S. forests remain a carbon sink through most of the coming century, sequestering 128 Tg C y–1. Constraining forestland to its current boundaries and constraining management to current levels reduce average sequestration by 25 to 28 Tg C y–1. An increase in demand leads to increased management and greater sequestration in forests. The results are robust to climate change.