A GP, or General Purpose class oil tanker can hold up to 8 million gallons of motor gasoline, and the next higher class, which is the MR, or Medium Range class, can carry up to 14.5 million gallons. Both the GP and MR class oil tankers can access most ports worldwide and are used for transporting refined petroleum products across short distances, such as between Europe and the United States East Coast. The LR1, or Long Range 1 class oil tanker is used for crude oil or refined petroleum products, can access most of the larger ports worldwide and is capable of holding up to 25.8 million gallons of gasoline.
The largest size oil tanker class is the ULCC, or Ultra-Large Crude Carrier class, which is used to transport crude oil worldwide. The ULCC oil tanker is capable of carrying up to 3.7 million barrels of crude oil, but the number of ports that can accommodate a vessel of this size are limited. In the U.S., the only port that can handle a fully-loaded ULCC oil tanker is the Louisiana Offshore Oil Port, or LOOP.
The first two ships built for transporting oil were sail-driven ships, and were constructed on England's River Tyne in 1863. The first steamer-ship made to carry oil was built in 1873, but its use was discontinued after safety concerns arose. The prototype versions of what eventually developed into the modern-day oil tanker were designed and constructed between 1877 and 1885.