What is the name of Norway’s longest river?

Norway’s longest river is the Glomma, also called the Glåma.

The Glomma runs for about 621 kilometres through eastern Norway before reaching the Oslofjord at Fredrikstad. Its source is in the mountainous area near Røros, and its route passes through important inland regions including Innlandet and Østfold.

The river has long supported transport, agriculture, timber floating, and industry. Hydroelectric power stations now use parts of its drainage system, making the Glomma important to Norway’s energy and economic history as well as its geography.

The Glomma is sometimes confused with rivers that are longer within particular Norwegian regions or drainage basins. The question asks for Norway’s longest named river itself; that distinction makes Glomma the canonical answer. Its lower course is especially significant near Sarpsborg and Fredrikstad.