How it started
Before 1945
The first steps towards building additional tracks for suburban service between Gdańsk and Sopot were taken in 1912. Station tracks were modified, and buildings were torn down on the planned route. The project was interrupted by the outbreak of World War I.
During the interwar period 1919 – 1939, the Tricity area was divided into two zones under two different governments. Gdańsk (Danzig) was a Free City not in Poland, while the new city of Gdynia was part of Poland. The transportation systems of the two zones were completely separate. Although rail transport in Gdańsk was operated by PKP, the city authorities of Gdańsk did not revive plans for an urban rail service.
World War II caused terrible devastation in Gdańsk. But after the war, the borders dividing the Tricity were abolished.
After World War II
When World War II ended in 1945, all of the Tricity became part of Poland.
From Wikipedia’s article on Tricity Rapid Transit Rail Ltd, shared under CC BY-SA 4.0.2