The single track, standard gauge line lacks electrification and only has centralized traffic control south of Røros Station.

Through Gauldalen the line largely follows the river Gaula, a section which is hilly with many curves and limited speed.

The start of the Røros Line would, however, be tied to two smaller railway projects which instead would serve regional needs.

After local initiatives, the Ministry of the Interior gave Carl Abraham Pihl the task of preliminary surveys of two routes.

The Trunk Line had been built by and was owned by an English company, and the government was not satisfied with the private arrangement.

Aiding in his cause, it was at the time not believed that the lines would ever connect, as lakes and rivers were seen as complementary to railways.

A group of forest owners petitioned that a 6-kilometer (3.7 mi) branch be built on the west shore in order to negotiate a difficult part of the river.

A channel was initially proposed and would have been slightly cheaper, but on 7 October 1859 Parliament approved that the line be extended to Grundset and that Elverum Station would be placed on the west shore.

[20] Proposals for an extension from Grundset to Åmot was made in 1864, which would allow the railway to connect to the steamships operating on Storsjøen, by placing the end station at Rena where the river Renaelva empties into Glomma.

Construction started soon after the parliamentary decision and was easy due to the flat valley the line was built through.

A challenge was that during the fall harvest many people returned to the farms, with only half the men left for construction work.

Another challenge was the reliable sourcing of lumber; forest owners were often not willing to sign contracts and the railway often had to cut its own timber.

It was followed by the 30.4-kilometer (18.9 mi) section from Støren to Singsås Station on 4 January 1876, although temporary freight traffic had been conducted since 12 February 1875.

[7] Operations on the Hamar Line initially consisted of a single daily round trip, increasing to two on weekdays from 1867.

The timing was not well-suited for local passengers, and from 1899 NSB operated an extra express train which corresponded with Hurtigruten.

[40] Hamar Station developed into a major center for the transhipment of goods between narrow and standard gauge rolling stock.

[51] By the 1920s it seem evident that the three remaining narrow-gauge mainlines, the Røros, Vestfold and Jæren Lines would be gauge converted.

Røros Copper Works shut down production in 1926, citing high transport costs caused by transshipment at Støren as one reason.

The other major works was to replace the branch line which Røros Station was built on with a semi-circular loop through the town.

[62] Steam locomotives were from 1951 partially replaced with Class 86 diesel multiple units, cutting travel time from Hamar to Røros to six hours.

Several weak points on the line were upgraded in 1964, allowing the even stronger Class 30 and 31 trains to be used, as well as Di 3 diesel locomotives.

[64] Regular use of Di 3s started on 30 May 1965, coinciding with the reintroduction of night trains on the line, running all the way from Oslo to Trondheim.

Combined with the closing of many smaller halts, they allowed travel time between Hamar and Røros to be cut by an hour.

[74] The stations between Hamar and Grundset, and Trondheim and Støre were designed by Georg Andreas Bull as his railway-architectural debut.

[79] Compared to the contemporary Trunk and Kongsvinger Lines, the narrow gauge railways were to be low-cost projects, which included scaling down the size of stations.

The architecture drew more from national inspiration, with Bull creating simple, often rectangular structures and Blix designing more creative stations.

[83] Two major developments have been proposed for the Røros Line – electrification and installation of centralized traffic control.

[74] The primary impact of electrification would be a severe cut in operating costs of the railway companies, and thus better margins for forest owners, who could increase their export.

Intermodule cargo trains operate from Oslo to Trondheim via the Dovre Line, despite its higher elevation, because of the electric traction.

[86] Need for this reserve is shown by the heavy rainfalls of storm Hans in early August 2023, leading to a bridge collapse on the Dovre line.