Are Daytime Running Lights Legal in the US?

Conditional

Daytime running lights are legal in the US and are allowed but not mandated by federal standard FMVSS 108. Adding or retrofitting DRLs is fine as long as they are the right color, within the brightness limits, and do not dazzle other drivers.

Why?

Unlike some countries, the US permits DRLs rather than requiring them, and FMVSS 108 sets how they must behave when fitted. They must show white or amber light at the front and stay within a maximum intensity so they aid visibility without glaring.

A retrofit therefore needs to respect those limits: DRLs that are excessively bright, the wrong color, or that flicker are non-compliant, and lights bright enough to dazzle oncoming drivers defeat the purpose. They also cannot stand in for the headlights after dark, when proper low beams are required.

So adding daytime running lights is road-legal when they meet the color and intensity rules and switch over to real headlights at night. A blinding or wrong-colored setup is not.

What decides if it's legal

Daytime running lights are permitted, not required, under federal standard FMVSS 108.
They must be white or amber at the front and within intensity limits.
They must not be so bright that they dazzle other drivers.
They must not mask or replace the required headlights at night.

Does it depend on your state?

The FMVSS 108 rules for DRLs are federal, so the color and intensity limits apply nationwide. States enforce lighting at inspection to differing degrees, but the standard is the same.

Related legality guides

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Sources

This page is general guidance, not legal advice, on the rules in the US for daytime running lights. The detail varies by exact vehicle and changes over time - confirm with your insurer and the EPA, NHTSA and your state DMV before modifying.