The Trans-Alaska Pipeline System (TAPS) is an oil transportation system spanning Alaska, including the trans-Alaska crude-oil pipeline, 11 pump stations, several hundred miles of feeder pipelines, and the Valdez Marine Terminal. TAPS is one of the world's largest pipeline systems. It is commonly called the Alaska pipeline, trans-Alaska pipeline, or Alyeska pipeline, (or the pipeline as referred to in Alaska), but those terms technically apply only to the 800 miles (1,287 km) of the pipeline with the diameter of 48 inches (1.22 m) that conveys oil from Prudhoe Bay to Valdez, Alaska. The crude oil pipeline is privately owned by the Alyeska Pipeline Service Company.

The pipeline was built between 1975 and 1977, after the 1973 oil crisis caused a sharp rise in oil prices in the United States. This rise made exploration of the Prudhoe Bay oil field economically feasible. Environmental, legal, and political debates followed the discovery of oil at Prudhoe Bay in 1968, and the pipeline was built only after the oil crisis provoked the passage of legislation designed to remove legal challenges to the project.

In building the pipeline, engineers faced a wide range of difficulties, stemming mainly from the extreme cold and the difficult, isolated terrain. The construction of the pipeline was one of the first large-scale projects to deal with problems caused by permafrost, and special construction techniques had to be developed to cope with the frozen ground. The project attracted tens of thousands of workers to Alaska, causing a boomtown atmosphere in Valdez, Fairbanks, and Anchorage.

The first barrel of oil traveled through the pipeline in the summer of 1977, with full-scale production by the end of the year. Several notable incidents of oil leakage have occurred since, including those caused by sabotage, maintenance failures, and bullet holes. As of 2014, it had shipped over 17 billion barrels (2.7×109 m3) of oil. The pipeline has been shown capable of delivering over 2 million barrels of oil per day but nowadays usually operates at a fraction of maximum capacity. If flow were to stop or throughput were too little, the line could freeze. The pipeline could be extended and used to transport oil produced from controversial proposed drilling projects in the nearby Arctic National Wildlife Refuge (ANWR).