Which grid system was the first used in the Philippines and predecessor of UTM?

• A. World Polyconic Grid
• B. Vigan Datum
• C. Philippine Transverse Mercator
• D. Mercator Grid System

Answer: (A)

The key idea is how a country maps its territory with a chosen projection and a grid of straight lines that can be read as eastings and northings. In the Philippines, the earliest widely used grid was based on the World Polyconic projection. This approach laid out a gridded network across the archipelago and provided practical coordinates for survey work before a standardized global system was adopted. Because it established a countrywide, metric-like grid using a polyconic setup, it directly paved the way for later, more uniform systems such as the Transverse Mercator family that culminated in UTM.

Understanding why this is the best answer also helps distinguish the other terms. A datum like the Vigan Datum refers to a reference surface for positions, not a grid network itself, so it isn’t the grid system that carried coordinates across the country. The Philippine Transverse Mercator represents a later, localized evolution toward a TM-based grid rather than the first grid used. The Mercator Grid System is a general projection used historically for navigation and maps but did not serve as the Philippines’ first, foundational national grid or its direct predecessor to UTM.