Barangay San Nicolas is also part of the Metro District Division of 76 Barangays in Tarlac City. Barangay Sto. Cristo bound it on the South, Barangay Matatalaib on the East, Barangay Sepung Calzada on the Northeast, Tarlac River on the North, and Barangay Poblacion on the West.

It is approximately 1.0 kilometer away from city proper. It has a total land area of 96.43 hectares designated to residential and industrial area. Different kinds of business establishments such as funeral homes and auto parts located here. It divided into 9 Blocks namely Block 1, Block 2, and Block 3 to Block 9.

Barangay San Nicolas classified as Urban Barangay, it has a total population of one thousand four hundred ninety eight (1,498) as of 2005, and a household population of one thousand five hundred fifty six (1,556).

Barangay San Nicolas is a residential, commercial and industrial area. Most of the people residing in this barangay were employees, laborers, construction workers, vendors, drivers, and so on. Some have their own business firms such as sari-sari stores, hardware, motor parts, electrical shops, and so on. Other businesses that popular here are Enriquez and Ilagan Funeral Homes.

Barangay San Nicolas is one of the major locations of business and commercial centers in Tarlac City today. This progressive barangay was once a sitio of Barangay Sto. Cristo. According to the elders, Juana Salvador caretaker of their Patron Saint saw the transformation of San Nicholas into a Barangay.

It was during the Japanese Era when San Nicolas became a separate barrio from its mother barrio Sto. Cristo because of its growing number of population. Their barangay named after their Patron Saint San Nicolas. Today, San Nicolas is one of the premiere centers of the City of Tarlac. Different establishments are located here such as schools, funeral homes, appliance centers, banks, and terminals, radio station, factory and others.

Families like Bueneventura were the first settlers who established and eventually became leaders in this Barangay.

Ninety percent of the total populations are Pampango, and the rest are Tagalog, Bisaya, Pangasinense, and Ilocano.

Barangay San Nicolas celebrates their feast day every 10th of September, as a thanksgiving to their Patron Saint is Saint Nicolas. Saint Nicholas is the patron saint of sailors, merchants, archers, children, and students.