What are some American-owned gas companies?

These are all the American-Owned Gas companies that I could find. Hope this helps :)

Alon USA

Arbusto Energy

Apache Corporation

Chevron Corporation

Anadarko Petroleum Corporation

BreitBurn Energy

Chem-Energy Corporation

Chief Oil & Gas

ConocoPhillips

Crown Central Petroleum

Devon Energy

ENSCO International

Eser Corporation

ExxonMobil

First Texas Energy Corporation

Flying J

Greka Energy

Hess Corporation

Koch Industries

Marathon Oil Corporation

Northern Oil & Gas

Occidental Petroleum

Plains Exploration & Production Company

Questar

Shell Oil Company

Sinclair Oil

Somerset Refinery

St. Mary land & Exploration

Tesoro

THUMS

United Refining Company

Vaalco Energy Inc.

Valero Energy Corporation

Venoco Inc.

XTO Energy