This is quite the amazing graph, the picture worth 100,000 words. Note the huge increase in natural gas generating capacity from 2000 to 2004. Those calling for a natural gas revolution should occasionally remind us that we've already had one.
There are many other illuminating maps and charts in this presentation by M.J. Bradley and Associates, Benchmarking Air Emissions of the 100 Largest Electric Power Producers in the United States
(via Post Carbon Institute)