What states allow green under glow on cars?

There is no US state that explicitly *allows* green underglow on cars. While some states may not have specific laws prohibiting it, most states have laws regarding vehicle lighting that are generally interpreted to prohibit underglow lighting of any color, including green, because it doesn't conform to standard lighting requirements for safety and visibility. These laws often cover things like:

* Illegal modifications: Altering factory-installed lighting systems is often prohibited.

* Improper lighting: Underglow is often considered improper lighting, as it doesn't serve a safety purpose and can be distracting to other drivers.

* Color restrictions: Many states specify allowed colors for vehicle lights, and green is typically not included.

Therefore, while you might not find a law directly stating "no green underglow," the existing laws regarding vehicle lighting almost certainly make it illegal in all 50 states. It's best to assume it's illegal unless a state explicitly states otherwise. Enforcement varies from state to state.