The municipality has a land area of 538.66 square kilometers or 207.98 square miles which constitutes 4.34% of Isabela’s total area. Its population as determined by the 2015 Census was 4,253. This represented 0.27% of the total population of Isabela province, or 0.12% of the overall population of the Cagayan Valley region. Based on these figures, the population density is computed at 8 inhabitants per square kilometer or 20 inhabitants per square mile.
Gamu has 16 barangays as shown in the following table.
According to the 2015 Census, the age group with the highest population in Gamu is 5 to 9, with 3,131 individuals. Conversely, the age group with the lowest population is 80 and over, with 261 individuals..
Combining age groups together, those aged 14 and below, consisting of the the young dependent population which include infants/babies, children and young adolescents/teenagers, make up an aggregate of 30.59% (9,149). Those aged 15 up to 64, roughly, the economically active population and actual or potential members of the work force, constitute a total of 64.17% (19,190). Finally, old dependent population consisting of the senior citizens, those aged 65 and over, total 5.23% (1,565) in all. The computed Age Dependency Ratios mean that among the population of Gamu, there are 48 youth dependents to every 100 of the working age population; there are 8 aged/senior citizens to every 100 of the working population; and overall, there are 56 dependents (young and old-age) to every 100 of the working population.
The median age of 26 indicates that half of the entire population of Gamu are aged less than 26 and the other half are over the age of 26.
The population of Gamu grew from 18,762 in 1960 to 29,904 in 2015, an increase of 11,142 people. The latest census figures in 2015 denote a positive growth rate of 0.81%, or an increase of 1,247 people, from the previous population of 28,657 in 2010.
The Municipality of Gamu is a 4th class municipality. Agriculture, Commercial and Service Center is the primary source of income and livelihood of the people of Gamu. Rice and corn are the major crops produced by the farmers.
According to the Bureau of Local Government Finance, the annual regular revenue of Gamu for the fiscal year of 2016 was ₱92,008,460.47.
- Annual Regular Income = Locally Sourced Revenue + Internal Revenue Allotment (IRA) Current Year + Other Shares from National Tax Collection
- Locally Sourced Revenue = Real Property Tax (General Fund) + Tax on Business + Other Taxes + Regulatory Fees + Service/User Charges + Receipts from Economic Enterprises