Lanao del Norte registered a total population of 473,062 persons in Census 2000, an increase of 32,279 persons from the1995 Census of Population. This figure translated to an annual growth rate of 1.53 percent, from 2.44 percent during the 1990 to 1995 period. The number of households also rose to 90,091, from 83,326 households in 1995. The average household size was 5.25 persons, almost the same as that of 1995 (5.29 persons) but higher than the national average of five persons.

The Census of Population and Housing (Census 2000) showed that the province of La Union recorded a total population of 657,945 persons. The figure was higher by 60,503 persons compared to the 1995 count. This increase translates into a 2.09 percent annual growth rate in the 1995-2000 period, higher than the annual growth rate (1.61 percent) in the 1990-1995 period. A corresponding increase of 10,585 households was also observed, from 116,994 households in 1995 to 127,579 households in 2000. This resulted to an average household size of 5.16 persons, slightly higher than the 5.11 average household size in 1995.

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.