The presence of Slav origin population at the end of 18th century in Slupsk cannot be ignored, though, it should be honestly said that percentage of this population was very small. Slupsk was made Prussian town more and more ethnically equal and completely religiously homogeneous. Within a period of Napoleonic Wars about 5.000 people lived in Slupsk. However, in 1875-1913 Slupsk doubled its own population, exceeding in 1913 - 35.000. Immigration of local people, inhabitants of small country towns and villages was only a part of great migration movements in eastern provinces of the Prussian-German State.

This phenomenon was called “Landflucht” – so-called escape to cities of country-folk in search of jobs and better conditions of existence. The mentioned occurrence liberated mass-escape from East of contemporary Germany, not only countrymen, but first of all inhabitants of cities, so called “Ostflucht” which in German industrial centres, sought fulfillment of their own vital aspirations. To 1870, emigration from Slupsk was sporadic. In 1880-1895 it embraced approx. 50 people annually, and later, at the end of 19th century emigrating people left, first of all (90%), to USA, Argentina and Chile.

Changes followed also in religious structure. In 1847 arose at the Church of St. Otto, catholic parish which number grew up to 950 people in 1905. Members of catholic society cannot be identified with Polish population. On the ground of city district arrived 1064 hoboes from Russian annexation in 1912. Polish workers built most probably narrow-gauge railway from Ustka to Smoldzino.

The Slovinian lingual territory was shrinking all the time. The general organization of elementary educational systems became a tool germanizing Slovinian population in XIX. Prussian authorities aimed to eliminate homilies in Kashubian dialect. Homilies survived in Cecenowo till 1876 and in Glowczyce till 1886. According to today's estimates, in 1880 on grounds situated around Lebsko and Gardno lakes inhabited approx 1000 Slovinian, while in 1911 explorer Rudnicki Nicholas counted on these rounds only 50 people speaking fluently in Kashubian language.

Jewish community in Slupsk counted 879 people in 1871. This number decreased to 160 people in 1905 mainly because of growing of anti-Semitic mood. At first these appearances, relied mainly on economic boycott of business establishments led by Jews. Later however, an escalation of violence followed. A dead centre was taking power by Nazis in 1933. Nazi fighting squads burnt Slupsk synagogue at "crystal night" on 9 to 10 of November 1938. The last act of tragedy took place on 10 of July 1942. Half thousand of Slupsk Jews, were sent from railway station with freight cars straight to gas chambers of Nazi extermination camp in Auschwitz.