While Ilocano migration to San Nicolas likely began in the early to middle part of the 18th century, it was not until around 1800 that a substantial influx occurred.

By the mid-nineteenth century, San Nicolas had developed significant infrastructure, including a state house, a schoolhouse, and a growing population.

Governor General Narciso Claveria y Zaldua issued a Royal Decree on June 18, 1846, officially separating San Nicolas from its mother parish of Tayug.

This decree, marked San Nicolas's formal elevation to a "pueblo parroco" and, by extension, affirmed its status as a civil township.

Don Mateo Miranda served as the incumbent governadorcillo at the time of the decree, with P. Jose Manso appointed as the first curate by the Dominican Province.

San Nicolas's inclusion in Nueva Ecija was primarily based on its historical ecclesiastical ties to Tayug and its status as an Augustinian parish.

Igorot laborers were employed to carry supplies and evacuate wounded as the rough terrain on the trail made it impossible for vehicles to enter.

It borders Tayug to the south, San Manuel to the west, Santa Fe to its northeast, Itogon to the north, and Natividad and Carranglan to its southeast.

[11] On the same day, the Nueva Vizcaya provincial board held a special session in Malico and issued a resolution requesting San Nicolas officials to refrain from building infrastructure projects within the barangay's boundaries.

Governor Ramon Guico III asserted Malico's affiliation with Pangasinan, emphasizing the province's commitment to enhancing local infrastructure and services regardless of the territorial dispute.

[14] Poverty Incidence of San Nicolas Source: Philippine Statistics Authority[20][21][22][23][24][25][26][27] San Nicolas, belonging to the sixth congressional district of the province of Pangasinan, is governed by a mayor designated as its local chief executive and by a municipal council as its legislative body in accordance with the Local Government Code.