Weekends are the most dangerous days, but for some, the weekend begins on Thursday.

Fatal accidents involving drivers with lower blood-alcohol levels start to tick upwards in the afternoon, but they remain stable. The drunkest drivers are on the roads after midnight.

These drivers have fewer fatal accidents at the levels the new proposal would outlaw.

Many drinks consumed quickly can lead to memory gaps, when drinkers cannot recall some or all events.

Even a small amount of alcohol can disrupt a driver’s ability to concentrate or do two things at once.

The National Transportation Safety Board recently recommended that states lower the current blood-alcohol limit of 0.08 percent to 0.05 percent. Fatal accidents involving drivers who have been drinking — even those with low blood-alcohol levels — vary sharply depending on a driver’s age and the time of day.

Young drivers are more likely to have accidents than older ones. But a visual analysis of national data on drunken driving puts the disparity into stark relief — and suggests whose lives might be saved by proposed legislation to lower the legal blood alcohol limit.

The recommendation, by the National Transportation Safety Board, asks the 50 states and the District of Columbia to lower the current limit of 0.08 percent to 0.05 percent, the standard in most industrialized countries.

Drivers younger than 26 cause the most auto fatalities in the United States, regardless of alcohol consumption. But 21 percent of young drivers involved in a fatal accident have some alcohol in their system — higher than other age groups. Researchers have shown that even a small amount of alcohol can disrupt a person’s ability to concentrate or do two things at once. For less experienced drivers, one or two drinks can cause the loss of reasoning and reaction time that results in a fatal crash.

“Young drivers have a far greater risk differential in the 0.08 to 0.05 range,” said Deborah A.P. Hersman, the board’s chairwoman. “Lowering the legal limit can make people more thoughtful about having the second, third or fourth drink — because every drink raises a driver’s crash risk level exponentially.”

More than 6,600 impaired drivers are involved in fatal accidents every year, causing the deaths of about 10,000 people. About half of those accidents are caused by drivers who have blood alcohol levels at or below 0.16 percent.

The chart here reveals that the red “hot spots” start with young drivers at even the lowest blood alcohol levels, and decline as drivers get older. If the proposed legislation is adopted by the states, young drivers and their passengers may be the biggest winners.