Drivers in the continental United States who used their headlights during the day would be just as likely to become involved in a collision as would drivers who did not use their headlights.

In many countries that are farther from the equator than is the continental United States poor daylight visibility is the single most important factor in automobile collisions.

The proportion of automobile collisions that occur in the daytime is greater in the continental United States than in the countries that have daytime headlight laws.

Fewer automobile collisions probably occur each year in countries that have daytime headlight laws than occur within the continental United States.

Daytime headlight laws would probably do less to prevent automobile collisions in the continental United States than they do in the countries that have the laws.