Helsinki

In the 20th century, Helsinki continued its growth.

An excerpt from the article 31 facts about Helsinki

The city was now home to more than 100.000 people, among whom about as many spoke Finnish as Swedish (most employees spoke Finnish). Local Helsinki slang (stadin slangi) developed among children and young people as a mixed Finnish-Swedish language as early as the 1890s and was also influenced by Russian. Since the 1950s, the slang began to become more Finnish.