[1] The first census in the Philippines in 1591, was based on tributes collected and yielded about 666,712 people in the islands.

However, the first official census in the Philippines was carried out by the Spanish government pursuant to a royal decree calling for the counting of persons living as of the midnight of December 31, 1877.

[3] The first census conducted by the U.S. military forces took place in 1903 to fulfill Public Act 467 which was approved by the United States Philippine Commission on October 6, 1902.

[4] A four-volume description of this census was on hand some years ago at the National Archives in San Bruno, California, but the volumes appear to have since been misplaced.

[citation needed] For years between the censuses, the PSA and its precursor agencies have been issuing estimates made using surveys and statistical systems.