New sources of crude oil from the Bakken region of North Dakota, the Eagle Ford and Permian basins in Texas, and western Canada have induced new routes for shipping crude oil to U.S. and Canadian refineries. While pipelines have traditionally been the preferred method of moving crude overland, especially to or from landlocked locations, they either are not available or have insufficient capacity to move all the crude from these new sources of production. Although much of this oil is now moving to refineries by rail, waterborne transportation is playing an increasing role in moving crude oil within North America. The quantity of oil moving by barge on the Mississippi River and its tributaries increased ten-fold from 2009 to 2013, and tanker shipments between the Gulf Coast and Atlantic Canada have grown at an even faster rate ( Figure 1 ). There are no current data on the amount of domestic crude oil moving by barge or tanker to refineries along the Gulf Coast, but it is believed to have increased significantly since 2012. Two aspects of the oil industry critically influence shipping patterns: (1) not all crude oil is the same and (2) each refinery is currently equipped to refine a certain blend of crude oils. Refineries in the Northeast are predominantly configured to handle crudes from the Bakken, Eagle Ford, and Permian regions, but cannot efficiently refine oil sands crude from western Canada. There is greater variety in the capabilities of refineries on the Gulf and West Coasts. Reconfiguring a refinery to handle a different type of crude is possible but may be costly. The feasibility of doing so depends on the relative costs of various types of crude, the projected availability of the various crude oils, and the price spread between crude oil and refined petroleum products such as gasoline and diesel fuel. The sudden shift toward domestic sourcing of crude oil raises issues regarding the safety and efficiency of the maritime component of this new supply chain. These fall into two main categories. One concerns the Coast Guard's role in preventing oil spills by regulating the safety of vessels and the training and working conditions of crews. The other has to do with the impact of the Jones Act, a 1920 law that restricts domestic waterborne transport to vessels built in the United States and crewed by U.S. citizens, which may now be affecting U.S. producers' decisions about how to ship crude oil and whether to send it to refineries in the United States or in Canada. The vast majority of U.S. refineries are located along the coast (including the Great Lakes) or an inland waterway. Most coastal refineries traditionally have been supplied by imported crude, and some lack pipeline connections and may not be equipped or have the space to receive crude by rail. For this reason, large amounts of oil are being moved out of production areas by truck or rail, but are being transferred to barges or tanker ships for the last leg of the trip to a refinery. Crude oil produced at Eagle Ford, TX, is conveniently located for waterborne transport due to its proximity to the coast. Some of it moves through the port of Corpus Christi, where outbound crude oil shipments nearly trebled from 2012 to 2013. The nearby port of Victoria, TX, has also experienced a dramatic increase in crude oil barge traffic. It appears that most of the Texas crude moving by vessel goes to coastal refineries in Texas and Louisiana or to the Louisiana Offshore Oil Port (LOOP), an offshore ship-to-pipeline transfer facility. A comparatively small amount of Eagle Ford crude oil moves by water to refineries in proximity to New York Harbor and the Delaware River, but much larger quantities seem to be going to refiners in Canada's Atlantic provinces. While much of the oil coming from the Bakken region moves to refineries by rail, there are now several well-established intermodal routes involving water transport. These include: rail to barge at St. Louis and Hayti, MO, and Osceola, AR, on the Mississippi River, to Gulf refineries; rail to barge at Hennepin, IL, on the Illinois Waterway, to Gulf refineries; rail to vessel at Albany, NY, on the Hudson River, to East Coast refineries; rail to Yorktown, VA, for coastal transport to East Coast refineries; rail to vessel at Anacortes and Vancouver, WA, for coastal transport to West Coast refineries. Pipeline to barge transfer is occurring at Cushing, OK, from where barges move the oil down the Arkansas and Mississippi Rivers to Gulf Coast refineries. New waterborne services moving crude oil from the Bakken or Texas generally do so with smaller vessels than the trans-oceanic tankers used to carry Alaskan and imported oil. The fleet can be divided into two broad categories: "brownwater" vessels operating on inland and near-shore waters and "bluewater" vessels operating in the open ocean. A river barge can hold 10,000 to 30,000 barrels of oil. Two to three river barges are typically tied together in a single tow, and thus a river tow of tank barges could carry 20,000 to 90,000 barrels. In addition to inland rivers, this type of barge configuration is used on the intracoastal waterway (an inland canal) along the coasts of Texas and Louisiana. River barges have speeds of about 4 to 5 miles per hour (mph). A coastal tank barge designed for open seas (an articulated tug-barge, or ATB) can hold 50,000 to 185,000 barrels. However, newer ATBs can carry 240,000 to 340,000 barrels, a capacity comparable to that of coastal tankers. Seagoing barges have speeds of about 10 knots (12 mph). In contrast to coastal tank barges, a river barge can be used in "drop and swap" operation—that is, the tugboat can drop a loaded barge at a facility where it can be used for storing product while the tugboat is free to make other barge movements—so that the relatively expensive self-propelled portion of the vessel is not tied up while unloading, as a tank ship would be. The tugs designed for ATBs sail poorly without the barge, so they seldom perform drop and swap operations. A coastal tank ship can hold 300,000 to 650,000 barrels. The coastal tankers that are being deployed to move Texas crude carry 330,000 barrels and are referred to as "handysize" or "medium range" tankers. Coastal tankers have speeds of about 12-15 knots. For comparison, tankers moving Alaska oil to the West Coast carry between 800,000 and 1.3 million barrels of oil and fall into the "Aframax" or "Suezmax" size categories. Very large or ultra-large crude carriers (VLCCs and ULCCs) that carry imported oil from overseas hold 2 to 3 million barrels. A crude oil pipeline moves between 400,000 and 800,000 barrels per day, enough to service the largest U.S. refineries. The unit trains that move Bakken and Texas crude oil can carry 70,000 to 80,000 barrels. Table 1 summarizes conveyances for moving domestic crude oil. As Table 1 indicates, the Jones Act-eligible fleet of crude oil tankers consists of 11 ships, all employed in moving Alaska crude oil to the U.S. West Coast or to a refinery in Alaska. Of the 86 seagoing barges, 42 can carry more than 130,000 barrels. While a tanker's capacity is better matched to the daily consumption rates of a single refinery than the capacity of a unit train or most barges, the limited fleet of Jones Act-eligible tankers has required some refineries with direct ocean access to ship domestic oil by barge or train or to continue to rely on foreign sources. Jones Act-qualified ATBs and product tankers are also used to lighter ocean-going crude oil tankers. Although it is technically feasible to do so, tank vessels do not readily alternate between carrying dirty oil (crude oil, residual fuel oil, asphalt) and refined (clean) petroleum products because the tanks would have to be extensively washed after carrying dirty product, a time-consuming and costly process. However, due to the recent increase in domestic crude oil production, particularly at Eagle Ford, some tonnage has shifted from the "clean" products trade to the crude oil trade. Tankers that used to carry refined product from the Gulf Coast to Florida (via the Port of Tampa) are now carrying crude oil because they can earn higher returns. Barges are replacing them to move refined products to Florida, a development that has been blamed for higher gasoline prices in Florida. The decline of oil imports from overseas may free up some of the lightering fleet for the domestic crude trade. If West Coast refineries source more crude from the Bakken or Canada rather than Alaska, this could also free up Jones Act tankers. One such tanker is believed to have been redeployed to move crude oil from the Gulf of Mexico to the West Coast via the Panama Canal. However, there is a limit to how many clean product tankers will switch to carrying crude oil. The crude oil boom has also led to a boom in U.S. refinery output, so there is also strong demand for clean product tankers. The most economic tank vessel size to deploy depends largely on voyage distance. The longer the voyage, the more incentive there is to use a larger vessel because of economies of scale at sea. The first VLCCs were built when the Suez Canal was closed in the late 1960s and tankers headed from the Persian Gulf to Europe and North America had to sail longer routes around South Africa.