by the end of the century had grown to more than 1200 inhabitants. Kajaani Town Hall was built in 1831, the former City Library in 1830, Kainuu's first elementary school in 1883, and Kajaani Church in 1896 as it grew into a notable settlement.

The paper industry took off in Kajaani in the early 20th century in particular. Kajaani Paper Mill was built in 1907 and was run by the firm Kajaani Oy, which had a capital of FMK 5,000,000 (£137,615) in 1948. Kajaani Oy was eventually acquired by Valmet in 1983,