Santo tomas
Shield: From the seal of the Province of La Union divided into 4 portions w/ the sun inside a small circle at the center against a background divided into 2 parts; blue on top, and red at the bottom.
Tobacco Plant & Plow: At the upper left portion of the shield: Farming as the town's principal source of income.
Earthen Jars: At the upper right portion of the shield: Pottery as the leading industry of the municipality.
Fishing Boat: At the lower left portion of the shield: Fishing and other sea-based industries, town's principal "cash" products.
Wheel: At the lower right portion of the shield: Post-harvest facilities and commerce.
Scroll: "naimpusoan nga panagserbi" (whole-hearted public service), town's motto.
Golden Yellow: Richness in aims and fullness of mind and heart.
Blue: Peace, justice, equanimity, tranquility,and calmness.
Red: Industry, initiative, activity and aggressiveness.
1764: Year the Municipality was founded.