The Federal Energy Regulatory Commission (FERC) has issued its Energy Market Assessment for the 2013-14 Winter (see here). Discussing northeast supplies, it states (among other things): "Closer and cheaper Marcellus Shale gas has largely displaced natural gas supplied to the Northeast via pipelines from the Southeast, the Mid-Continent, and Canada. Supplies from the Southeast, Mid-Continent. and Canada have fallen from around 12 Bcfd in 2008 to less than 6 Bcfd in 2013, while Northeast production has increased from 2 Bcfd to over 11 Bcfd."
See the whole thing.