The smallest municipalities in Gipuzkoa are expected to lose population in the next decade, according to Eustat's latest projections. These figures forecast that by 2035, 27% of residents will be over 65 years old, an increase from the current 21.7%. A notable exception will be Belauntza, this municipality in Tolosaldea will experience a 25.5% growth, reaching almost 400 inhabitants.
Overall, the territory is projected to gain nearly twenty thousand inhabitants, a 2.5% increase, primarily due to a positive migration balance. However, this growth will not be uniform across all municipalities. Leintz-Gatzaga will have the highest proportion of elderly residents, with 39% of its population aged 65 or over. Orexa also stands out, with a 15.6% increase in that percentage.
Conversely, Baliarrain will have the lowest percentage of older residents (18%), and Belauntza is the only municipality where the proportion of seniors will decrease (from 23.9% to 22%).
Eustat has indicated that, of the 54 Basque municipalities, 6 are located in Álava, 20 in Gipuzkoa, and 28 in Bizkaia. Population losses will primarily be concentrated in smaller municipalities; 31 of them had fewer than 2,000 inhabitants in 2025.
In Gipuzkoa, half of these declines will occur in towns with fewer than 2,000 inhabitants, such as Segura, Olaberria, Altzo, Alkiza, Larraul, Leintz-Gatzaga, Arama, Altzaga, Beizama, and Orexa. Arama (-20.3%), Beizama (-15.1%), and Leintz-Gatzaga (-12.9%) show the largest losses. Errenteria will also experience a slight decrease (0.2%).
The territory's more significant municipalities, however, will gain population. Both Donostia and Irun will grow by approximately 3%, as will neighboring municipalities like Usurbil, Lezo, Oiartzun, and Hondarribia.
