On June 5, 1901, a convention was called on whether or not the province of Manila should annex the province of Morong, which was found to be unable to be self-sufficient as a province. Eventually, on June 11, Act No. 137of the First Philippine Commission abolished Morong and created a new province, named after the Philippines' national hero, Jose Rizal, who, coincidentally, was a native of Laguna. The new province comprised 29 municipalities, 17 from Manila and 12 from Morong. In 1902, Macario Sakay, a veteran Katipunan member, established the Tagalog Republic in the mountains of Rizal. Ultimately, Sakay's Tagalog Republic ended in 1906 when he and his men were betrayed under the guise of holding a national assembly aimed at the self-determination of the Filipino people.

On September 7, 1946, the Third Philippine Republic enacted Republic Act No. 14, which renamed the province of Tayabas to Quezon, in honor of Manuel Quezon. Quezon was the second President of the Philippines and a native of Baler (now part of Aurora). In 1951, the northern part of Quezon became the sub-province Aurora, named after Quezon's wife.

On September 24, 1972, President Ferdinand Marcos enacted Presidential Decree No. 1, which organized the provinces into 11 regions as part of Marcos' Integrated Reorganization Plan. The IRP created Region IV, known as the Southern Tagalog region, and was the largest region in the Philippines. At this time, Region IV consisted of Batangas, Cavite, Laguna, Marinduque, Oriental Mindoro, Occidental Mindoro, Quezon, Rizal, Romblon, and Palawan. In 1979, Aurora formally became a province independent of Quezon and was also included in Region IV.

On May 17, 2002, President Gloria Macapagal-Arroyo signed Executive Order No. 103, which made reorganized to the Southern Tagalog region. Due to its size, Region IV was split into two separate regions, Region IV-A (Calabarzon) and Region IV-B (MIMAROPA). Aurora was transferred to Region III, Central Luzon. The next year, Arroyo signed Executive Order No. 246, which declared Calamba as the regional center of the region.