A little research on how we use natural gas in this country came up with these stats here (a bit old- EIA 2000)

 NG is 24% of energy used in US.

NG used by sector:

Electric generation 24%
Residential - 22%
Industrial - 32%
Commercial - 14%
Other - 8%

84% of NG used in Industry is consumed in pulp and paper, metals, chemicals, petroleum refining, stone, clay and glass, plastics, and food processing industries.  

Yeah, and what's been happening in response to higher natural gas prices is increasing movement of fertilizer and petrochemical industries offshore to places that have plenty of NG still. Eg something like half of the US fertilizer industry has shut down in the last 5 years, since 95% of the cost of fertilizer is the natural gas. There's probably a lot more of this kind of thing to go - bad for the trade deficit.