How are polands three main cities related to the country's politics sea trade and history?

The Three main cities of Poland are:

Warsaw, Kraków, and Gdańskate

Warsaw had the highest population in Poland, which provide the country with the largest amount of labor forces for its economy and a place where political activities in Poland is centered.

Gdansk is located in the sea coast, so it became the center of sea trade and shipbuilding in the country.

Krakow had valuable historical value since it still preserves the look of medieval city in Poland.