Around 1840, merchants from Pelion and elsewhere came to settle in the fast-growing new city of Volos. In 1858, population was 400; by 1865, it had risen to 3,000. In 1881, the year of the annexation of Thessaly to Greece, Volos had a population of about 5,000, of whom 300 were Jewish and 600 Muslim. During the same period, some 300 Catholics were also registered: Italian and French technicians and workers, French and Austrian merchants, persons of various occupations from the Cyclades. In the early twentieth century, Volos was a culturally diverse city; plenty of opportunities to find work in the great number of factories and a vibrant commercial activity attracted many new residents, mainly from the villages of Pelion and Thessaly.
In 1907, families from Eastern Rumelia settled in Nea Anchialos and Efxinoupoli, 500 and 200 families respectively. In the 1920s, the population diversity increased further, with the arrival of refugees. Between 1921–1924, some 14,000 refugees from Asia Minor and Pontus came to settle in the city; the last Muslims left for Turkey after the Treaty of Lausanne (1923). Shortly before the declaration of the Greco-Italian War, refugees from Pontus arrived in the city and, from the 1950s onwards, the city’s return to prosperity attracted internal migration from Thessaly and Epirus. In 1960, the permanent settlement of Roma began and, from 1990 onwards, of economic migrants from the former Soviet Union and the Balkans.