English: This image from the International Space Station shows 18 km (11.2 mi) of Intracoastal Waterway, the 4800 km-long (3000 mi) barge channel that lies on the protected inshore of the coastal islands of the southern and eastern USA, including coastal Texas. The small city of Port Aransas lies on a barrier island fully 18 km (11.2 mi) seaward of the mainland and its sister city, Aransas Pass (image lower left). This image shows parts of the waterway that are artificial, as in the straight sector leading into Corpus Christi Bay. (Corpus Christi lies outside the lower margin of the image.) Other sectors of the waterway are natural bays such as Aransas Bay. Jetties protect the inlet into the Gulf of Mexico (image top right). Inlets at many points cut through the barrier islands to give shipping access to the Gulf of Mexico and the Atlantic Ocean. Several large rivers allow access from the waterway to distant inland ports, as in the cases of the Mississippi and Hudson Rivers. A recent study concluded that barge shipment in the Gulf Coast sector of the waterway remains the least-cost alternative for many commodities, with petroleum and petroleum products amounting to 30% of the total tonnage.