This region, for the most part, is one of semi-arid plains planted with wheat and in some places, especially near Aranda de Duero, in wine grapes, in the Ribera del Duero wine region. Sheep rearing is also still important.

Then, for 112 km, the river forms part of the national border line between Spain and Portugal, in a region of narrow canyons, making it an historical barrier for invasions and a linguistic dividing line. This isolated area has now a protected status: the International
Once the Douro enters Portugal major population centres are less frequent. Except for Porto and Vila Nova de Gaia, at the river mouth, the only population centres of any note are Foz do Tua, Pinhão and Peso da Régua. Tributaries are small and flow into canyons to enter the larger river. The most important are the Coa, the Tua, and the Tâmega. None of these small, fast flowing rivers are navigable.

These upper reaches of the Douro have a microclimate allowing for cultivation of olives, almonds, and especially grapes important for making the famous Port wine. The region around Pinhão and São João da Pesqueira is considered to be the centre of Port wine, with its picturesque quintas or farms clinging on to almost vertical slopes dropping down to the river. Many of these quintas are owned by multinational wine companies and are worth a visit.

Traditionally, the wine was taken down river in flat-bottom boats called rabelos, to be stored in barrels in cellars in Vila Nova de Gaia, just across the river from Porto. In the 1950s and 1960s dams were built along the river ending this river traffic. There are nine dams on the Portuguese Douro alone making the flow of water uniform and generating hydroelectric power. Now Port wine is transported in tanker trucks.

Recently, a prosperous tourist industry has developed based on river excursions from Porto to points along the Upper Douro valley. Boats pass through the dams by way of locks.