ExxonMobil Baytown Refinery, Texas

With a refining capacity of up to 584,000 barrels per day, this is often ranked as the largest refinery in the United States. And with 2,400 acres of intensely industrialized land within its perimeter, this is one of the largest industrial sites in the nation. In addition to the refinery, the larger complex includes two chemical plants, a regional engineering office, and a global technology center - extending for five square miles. Collectively, many basestocks are produced here e.g. butyl, polypropylene, and polyethylene, for both industrial and consumer applications. The refinery opened in 1919, by the Humble Oil Company, which later became Exxon. The 2.5 mile wide plant employs over 4,000 people. ExxonMobil is based in Irving, Texas, near Dallas.