With a total length of 621 kilometres (386 miles), it has a drainage basin that covers 13% of Norway's surface area, all in the southern part of the country.

The combination of raw materials, water power, and easy transport has over the centuries encouraged industry along the Glomma.

Some of the country's largest manufacturing and processing concerns are found around its mouth, where supplies of timber and hydropower have been backed by excellent port facilities.

The upper limit of the Glomma valley farms is variable, but typically runs about 500 metres (1,600 ft) in Østerdalen, slightly lower than in the Gudbrandsdalen, which reflects the colder climate.

Some of the vast amount of silt that the Glomma deposits in Lake Øyeren is extracted to manufacture LECA building blocks widely used for in the construction of foundations in Norway.