Which force has the greatest range among the four fundamental interactions?

Among the fundamental forces, gravity and electromagnetism both have infinite theoretical range because their carriers are massless or, in gravity's case, effectively long-ranged in general relativity. In practice, gravity is the dominant large-scale force because mass is always positive and accumulates. That makes it crucial across planetary, stellar and galactic distances. Electromagnetic forces usually cancel out in neutral matter, so their large-scale effect is much less dominant. For broad cosmic structure, gravity is the interaction that shapes the universe's architecture.