Map - Nord-Trøndelag (Nord-Trøndelag Fylke)

Nord-Trøndelag ("North Trøndelag") was a county constituting the northern part of the present-day Trøndelag county in Norway. The county was established in 1804 when the old Trondhjems amt was divided into two: Nordre Trondhjems amt and Søndre Trondhjems amt. In 2016, the two county councils voted to merge (back) into a single county on 1 January 2018.

As of 1 January 2014, the county had 135,142 inhabitants, making it the country's fourth-least populated county. The largest municipalities are Stjørdal, Steinkjer—the county seat, Levanger, Namsos, and Verdal, all with between 24,000 and 12,000 inhabitants. The economy is primarily centered on services, although there are significant industries in agriculture, fisheries, hydroelectricity and forestry. It has the lowest gross domestic product per capita of any county in the country.

Nord-Trøndelag covered 22412 km2, making it the sixth-largest county, and it consisted of 23 municipalities. The district of Innherred runs along the east side of the Trondheimsfjord, and is the most populated area, with much farming. To the south lies the district of Stjørdalen, while in the north, the larger district of Namdalen stretches from the Norwegian Sea to the mountains bordering Sweden. West of the Trondheimsfjord lays Fosen. Nord-Trøndelag bordered Sør-Trøndelag county to the south and Nordland county to the north. The western part of the county has several large valleys and consists largely of unpopulated wilderness, including four national parks. Snåsavatnet is the largest lake, while major rivers include Namsen, Verdalselva and Stjørdalselva.

Innherred was an important area during the Viking Age and featured the Battle of Stiklestad. The county was created in 1804 and was known as "Nordre Trondhjems amt" until 1919. Since the 1950s, the county has experienced a population growth below national levels. The axis north–south through the country past Grong and along the west side of Trondheim Fjord is a main transport artery, including the European Route E6 and the Nordland Line.

Nord-Trøndelag bordered Nordland to the north, Sør-Trøndelag to the south, Sweden to the east and the Norwegian Sea to the west. The county seat was the town of Steinkjer, with 20,527 inhabitants (2005). The largest lake is Snåsavatnet and the largest river is Namsen, one of the best salmon rivers in Europe. Other well known salmon rivers are as Verdalselva and Stjørdalselva. Salsvatnet is the second-deepest lake in Europe, with a maximum depth of 482 m. Another lake in the area is Byavatnet. Stjørdal is the biggest town in the county. There are local hospitals in Levanger and Namsos.

A large part of the population lives near the large Trondheimsfjord, which is a central feature of the southern part of this county. In the north are other fjords, mainly the Namsenfjord and Foldafjord. Areas on the eastern and northeastern shore of Trondheimsfjord (mainly in Stjørdal, Frosta, Levanger, Inderøy, Verdal and Steinkjer) are fertile agricultural lowland, with grain fields and vegetables. Together with the grain fields in the Namdalen lowland, this forms the most northern grain cultivation area in Norway today.

However, the spruce dominated forest (some birch) covers a much larger area, and Nord-Trøndelag is the second largest timber producing county in Norway (after Hedmark). The forest and highland in Nord-Trøndelag is one of few places in Norway with four species of deer (moose, roe deer, red deer and reindeer). There are mountains near the border with Sweden, and coastal mountains with bare rock at the northern coast. The spruce forests occurs even at the coast, where some areas are classified as temperate rainforest (boreal rainforest, see Scandinavian coastal conifer forests). There are several national parks in the county, among them Blåfjella–Skjækerfjella National Park (one of the largest in Norway), Børgefjell National Park (partly), Lierne National Park and Skarvan and Roltdalen National Park (partly).