2Dissolved and divided among neighboring (sub-)provinces.
3Became the only sub-province remaining in Mountain Province in 1966 and consequently assumed the name of the parent province.
4Became the only sub-province remaining in Agusan in 1914 and consequently assumed the name of the parent province.
5Reduced to the downtown area of present-day Isabela City in 1973; dissolved in 1975.
6From 1948 to 1954, Legazpi City comprised the present-day territories of Legazpi and Daraga. The city was dissolved in 1954 into its two former constituent municipalities. Legazpi became a city again in 1959.