The transportation of natural gas, crude oil and other liquids by pipeline has unique attributes that make customs reporting and accounting difficult, and easy to miss altogether. A pipeline is buried in the ground, out of sight and mind. The hydrocarbons continue moving to their destination as if the border does not exist. Crude oil and other liquids move in consecutive batches, like rail cars on a train of infinite length. Natural gas moves in a continuous stream, with all shippers’ goods commingled. A shipper does not own any particular molecules in the stream, and takes instant delivery of different molecules than it put in.