San Carlos City was once known as Binalatongan. From the time of its founding up to the middle of the 19th century, it was considered as the biggest and most populous town of Pangasinan composing a whole third of the Province. It is recorded in history as a bastion of freedom fighters, with famous uprisings against Spaniards led by Andres Malong (1660) and Juan dela Cruz Palaris (1762). These heroic acts prompted the Spanish colonizers to change the name of the town to San Carlos in honor of King Carlos III of Spain.

San Carlos became a city by virtue of Republic Act No. 4487 signed on June 19, 1965.

The city is a landlocked component city in the coastal province of Pangasinan  and has a land area of 169.03 square kilometers or 65.26 square miles which constitutes 3.10% of Pangasinan's total area. Its population as determined by the 2020 Census was 205,424. This represented 6.49% of the total population of Pangasinan province, or 3.88% of the overall population of the Ilocos Region.   Based on these figures, the population density is computed at 1,215 inhabitants per square kilometer or 3,148 inhabitants per square mile.

The city center of San Carlos is situated at approximately 15° 56' North, 120° 21' East, in the island of Luzon. Elevation at these coordinates is estimated at 10.8 meters or 35.4 feet above mean sea level.

Based on the great-circle distance (the shortest distance between two points over the surface of the Earth), the cities closest to San Carlos are Dagupan, Pangasinan, Urdaneta, Pangasinan, Alaminos, Pangasinan, Tarlac City, Tarlac, Baguio, and Muñoz, Nueva Ecija. The nearest municipalities are Malasiqui, Pangasinan, Calasiao, Pangasinan, Basista, Pangasinan, Santa Barbara, Pangasinan, Urbiztondo, Pangasinan, and Aguilar, Pangasinan.  Its distance from the national capital is 162.61 kilometers (101.04 miles). The following list delineates such distance measurements.

Nearest Towns

• Malasiqui, Pangasinan, 7.07 kilometers (4.39 miles) to the East (S84°E)

• Calasiao, Pangasinan, 9.20 kilometers (5.72 miles) to the North (N6°E)

• Basista, Pangasinan, 9.94 kilometers (6.17 miles) to the Southeast (S35°E)

• Santa Barbara, Pangasinan, 10.16 kilometers (6.31 miles) to the Northeast (N35°E)

• Urbiztondo, Pangasinan, 11.58 kilometers (7.20 miles) to the South (S9°W)

• Aguilar, Pangasinan, 12.46 kilometers (7.74 miles) to the West‑Southwest (S70°W)

Nearest Cities

• Dagupan, Pangasinan, 12.96 kilometers (8.06 miles) to the North (N7°W)

• Urdaneta, Pangasinan, 24.04 kilometers (14.94 miles) to the East‑Northeast (N77°E)

• Alaminos, Pangasinan, 46.90 kilometers (29.14 miles) to the West‑Northwest (N57°W)

• Tarlac City, Tarlac, 55.16 kilometers (34.27 miles) to the South‑Southeast (S28°E)

• Baguio, 59.80 kilometers (37.16 miles) to the North‑Northeast (N26°E)

• Muñoz, Nueva Ecija, 63.99 kilometers (39.76 miles) to the East‑Southeast (S68°E)

*** Distance from Manila: 162.61 kilometers (101.04 miles) to the South‑Southeast (S25°E)