New Jersey and New York City need more natural gas. There’s plenty of Marcellus natural gas produced in Pennsylvania. There’s also a big interstate pipeline, called the Tennessee (one of many pipelines) that carry natural gas from Pennsylvania and other states into northeastern markets including NJ and NYC. In order to meet growing demand, the Tennessee previously applied for and received approval from the Federal Energy Regulatory Commission (FERC) to expand their pipeline.
The expansion plans have not been without controversy (see this MDN story). The latest controversy revolves around a planned route for a 7-mile portion of the expansion in New Jersey.