What is the most common material for yard signs?

Corrugated plastic, often called Coroplast, is the most common yard sign material because it balances low cost with real outdoor durability.

• Lightweight and waterproof: easy to handle and unbothered by rain.
• Rigid on stakes: the fluted polypropylene structure keeps signs stiff on wire stakes.
• Weather resistant: holds up to UV exposure and temperature swings.
• Standard build: most political, real estate, and event signs use 4mm thickness.