The youngest Province in Cagayan Valley Region II consist of only six (6) municipalities namely Cabarroguis, (its capital) Diffun, Saguday, Aglipay, Maddela and Nagtipunan. During its creation on the year 1970 it has an estimated population of 49,767. After twenty (30) years of existence, on census year 2000 it has a total population of 147,100 with a 2.50% annual growth rate.

              Quirino Province acquired its juridical personality as a result of the division of the Province of Nueva Vizcaya on June 18, 1966 under R.A. 4734. It was named in the honor of the then President Elpidio A. Quirino. The municipalities of Diffun, Maddela, Saguday and Aglipay composed the newly born sub-province and the first elected Lieutenant Governor in the 1967 general elections was Hon. Jose B. Aquino.

              On June 21, 1969, three years after its birth as a sub- province, R.A. 5554 was enacted amending R.A. 4734 creating the Municipality of Cabarroguis taken from portions of the municipalities of Diffun, Saguday and Aglipay. The Act was introduced and sponsored by former Congressman Floro S. Crisologo and Melanio T. Singson.

              Finally, R.A. 6394 was passed on September 10, 1971 further amending R.A. No. 5554 separating the sub-province of Quirino from its mother province of Nueva Vizcaya constituting into a regular province. Hon. Leonardo B. Perez former Congressman, Senator, Chairman of the Commission on Elections and Concurrently the Political Affairs Minister and Hon. Benjamin B. Perez, former Congressman and Assemblyman for Region II at the Interim Batasang Pambansa(IBP), had worked for the passage of R.A. 6394.

             A portion of this province was formerly a part of the province of Isabela which was recovered and restored to the province of Nueva Vizcaya by the late Congressman Leon Cabarroguis for which the provincial capital was named in his honor.