The last new streetcar line established in Copenhagen was line no. 20, which began running in 1927.

The line was a rather short one, and often it was used for trials with special wagons, because if a trial could succeed at the line the wagon could also be used at the other lines.

The last day for the line to be a streetcar line was February the 10th 1958. The nickname of the line was: The Mountain Railway because the line was passing many hills.