The EPA has organized its data on major greenhouse gas emitters into a handy interactive map. You can zoom in on your area to see where the emissions come from near you, or scan around for the worst offenders. 

This map covers facilities that emit 25,000 metric tons or more of GHGs every year, so it's not like this map shows the sources of all of the country's emissions. There's no transportation, or residential, or agricultural facilities represented. But you're looking at more than half of the United States' GHGs, including all the major polluters.