The city of Gdańsk used Polish stamps with overprints from 1925 until 1938. These overprints read ‘PORT GDAŃSK’.
At the time, the city was part of a larger semi-autonomous city-state called the Free City of Gdańsk (in Polish, Wolne Miasto Gdańsk). Poland continued to handle its postage stamps even after the Nazis took over the Free City’s government in 1933.
Gdańsk’s own stamps, 1938
In 1938, Poland issued a new set of postage stamps for Gdańsk in four different denominations; these stamps were the only to be inscribed PORT GDAŃSK (in small letters, next to the much more prominent POCZTA POLSKA). In 1939, Hitler invaded Poland and abolished the Free City, adding it to Poland where it remains to this day.
