Recent advancements in natural gas extraction (e.g. hydraulic fracturing) have significantly increased natural gas reserves in the United States. Estimates of the technically recoverable natural gas (TRR) in the Marcellus range between 141 trillion cubic feet (TCF) and 489 TCF. However, TRR estimation does not incorporate existing policies, regulations, or land use. We find that approximately 48% of the Marcellus in New York and Pennsylvania is inaccessible given land use patterns and current policy. In New York, approximately 83% of the Marcellus is inaccessible; while in Pennsylvania about 32% of the Marcellus is off limits to drilling. The New York portion of the Marcellus is estimated to have a TRR of between 19.9 TCF and 68.9 TCF. We estimate that 79% of the resource is inaccessible, which results in an accessible resource estimate of between 4.2 TCF and 14.4 TCF. In Pennsylvania, the shale gas TRR is estimated at 86.6-300 TCF. However, we estimate that 31% of the resource is inaccessible, which results in an accessible resource estimate of between 60.0 TCF and 208 TCF. (C) 2012 Elsevier Ltd. All rights reserved.