States near the Marcellus Shale, a huge natural gas formation centered in Pennsylvania, are feverishly pursuing a $4 billion ethane “cracker†to be built by Royal Dutch Shell. The cracker will process ethane-rich gas from the Marcellus Shale into ethylene, and the ethylene will be used by the pharmaceutical, chemical and plastics industries. The plant will create 10,000 construction jobs and several hundred permanent jobs.