The province encompassed much of the central section of the Cordillera mountains in Luzon.

[1] Included in the new province's territory were the Spanish-era comandancias of Amburayan, Bontoc and Lepanto, which became its three component sub-provinces.

[1] This territory, corresponding to the lower Chico River basin, was later organized into the sub-province of Kalinga through Act No.

[2] The province was slightly enlarged when Tagudin, the coastal town at the mouth of the Amburayan River, was detached from Ilocos Sur and made the capital of the sub-province of Amburayan on May 15, 1907, by virtue of Act No.

[3] On August 18, 1908, the Philippine Legislature annexed all four of Lepanto-Bontoc's sub-provinces to the Mountain Province through Act No.