Houston is where they're located. Maybe some admin offices in New Orleans or onshore oil and gas, but it has more banking/finance/trade/ports/ships industry than offshore and major companies. The Baton Rouge - New Orleans corridor of the Mississippi is home to lots of shipping and chemical industry, but most oil and gas refining is between Lafayette and Houston. Houston is home to some major corporations and quite a few smaller groups as well. Philips, Conoco, Marathon, Halliburton, Baker Hughes, Anadarko, EOG, Kinder Morgan, Plains All American (Pipeline), Centerpoint (home distribution), Varco, Apache are all Fortune 500 companies headquartered in Houston with some relationship to the oil and gas industry (yes, I used wiki). That's not to mention all the jobs from other companies in the industry (Chevron, etc) with headquarters elsewhere. New Orleans I think has only 1 Fortune 500 company.
