Population growth rate at 2.25 percent

The total population of Isabela, as of May 1, 2000, was 1,287,575 persons. This implied an increase of 156,854 persons over the 1995 census figure or an average annual growth rate of 2.25 percent. This was 0.90 percentage point higher than the average growth rate recorded in 1995 (1.35 percent). A corresponding increase on the number of households was also registered, from 233,203 households in 1995 to 254,982 households in 2000. This resulted to an average household size of 5.05 persons, higher than the national average of five persons.

Ilagan, the provincial capital, the largest in terms of population

Among the 35 municipalities and two cities in Isabela, Ilagan, the capital of the province, was the largest in terms of population size with 119,990 persons or 9.32 percent of the total population of the province. This was followed by the City of Santiago (8.58 percent) and Cauayan (8.07 percent). All other municipalities had less than five percent each. Maconacon, the least populated municipality accounted for only 0.29 percent of the total population of the province.

Isabela, the most populated in Cagayan Valley

Isabela was the most populated among the five provinces in Cagayan Valley (Region II), comprising 45.7 percent of the 2.8 persons in the region. At the national level, the province contributed 1.7 percent to the total population of 76.5 million.

Median age of 20 years

Isabela had a median age of 20 years, the same as that of the 1995 figure. This meant that about half of the total population of the province were below 20 years old.

Sex ratio recorded at 105.4

For all ages, the sex ratio in Isabela was about 105 with 660,627 males and 626,948 females in the 2000 Census of Population and Housing (Census 2000). There were more males than females below 50 years old.

Close to three dependents for every four economically active persons

About 60 percent belonged to the economically active population (aged 15 to 64 years) while 37.66 percent were young dependents (aged 0 to 14 years) and less than four percent, old dependents (aged 65 years and over). The overall dependency ratio in 2000 was 70.31. This meant that for every 100 persons aged 15 to 64 years; there were about 66 young dependents and four old dependents, an improvement of 2.2 percentage points over the 1995 figure of 73.5.

More males belonged to the voting population than females

There were 719,577 persons or 55.89 percent of the total population belonging to 18 years old and over (voting population). Among them, the proportion of males (51.06 percent) was slightly higher than females (49.94 percent).

About half of female population were in the childbearing age group

Out of 626,948 total female population, 338,213 or 53.95 percent belonged to childbearing or reproductive age group (15 to 49 years).

Nearly 20 thousands were incoming Grade I pupils

Potential grade 1 pupils were those five or six years old and had completed pre–school education. In the Census 2000, there were 19,627 children or 1.74 percent of the total household population five years and over in Isabela, of which 49.61 percent were boys and 50.49 percent girls.

Females dominated higher levels of education

About 48.36 percent of population five years old and over had attended or completed elementary education; 27.31 percent, high school; and 3.35 percent, post secondary education. Less than four percent were academic degree holders while 9.07 percent had some units in college. A small proportion (0.44 percent) pursued post-baccalaureate studies. There were more males than females among those who had attended or finished elementary (52.35 percent), high school (51.05 percent) and post secondary courses (50.15 percent). However, females dominated higher level of education such as college undergraduates (50.86 percent), academic degree holders (58.95 percent) and post baccalaureate (61.36 percent).

Ilocano was the most prominent ethnic group

Ilocano was the most prominent ethnic group in Isabela. Of the total household population, 68.71 percent classified themselves as Ilocanos. The next two prominent ethnic groups were Ibanag (14.05 percent) and Tagalog (10.02 percent). The remaining 7.22 percent were either Gaddang, Paranan, Yogad, or were from other ethnic groups.

About 49 percent were married

Married persons accounted for 49.21 percent of the total persons 10 years old and over, lower by 2.82 percentage points than the 1995 figure (52.03 percent). Single persons comprised 43.40 percent in 2000, from 42.57 percent in 1995. The widowed (4.22 percent) had less than one percentage point difference with the proportion registered in 1995 (3.95 percent). Those in other marital arrangements constituted 2.22 percent, an increase of 1.20 percentage points from the 1995 figure (1.02 percent).

Four in ten housing units had floor area of less than 50 square meters

Four in ten occupied housing units had floor area of less than 50 square meters (78.38 percent). About 23 percent had floor area of 30 to 49 square meters. Almost an equal proportion (22.13 percent) had floor area of 20 to 29 square meters. Less than three percent of the occupied housing units had floor area of 120 and over square meters.

A large proportion (96.58 percent) of the occupied housing units in Isabela in 2000 were single houses. About two-thirds (65.32 percent) of the occupied housing units did not need repair or with minor repair only while 21.55 percent needs major repair. Almost one-third (33.44 percent) of the occupied housing units were built from 1996 to 2000.

Three out of four housing units had roof made of galvanized iron/aluminum

Out of the 249,742 occupied housing units in Isabela, the proportion with roof made of galvanized iron/aluminum was 73.33 percent, an improvement of 21.49 percentage points from the 1990 figure (51.84 percent).

As to the combination of construction materials used for roof and outer walls, two out of five of the occupied housing units were made of galvanized iron/aluminum as roof and concrete/brick/stone as outer walls, almost four times higher than the 1990 figure (13.04 percent).