Researchers from the Insurance Institute for Highway Safety analysed data from the national Fatality Analysis Reporting System for the years 1986 to 2002 to see if they could identify any trends in the timing and severity of car crashes.
They compared days with relatively high numbers of car crash deaths with the two days exactly one week before and week afterwards, in a bid to rule out any anomalies in the figures.
The analysis showed that on average 117 people die on US roads every day, but the death toll ranged from 45 to 252 deaths on any one day.
There were more road deaths during summer and autumn than during winter and spring, largely because of the increased volume of traffic on the roads, suggest the authors.
There were more deaths in August than any other month, and more deaths from June to November than from December to May. The fewest deaths occurred in January and February, but far fewer journeys were made during these months.
Specific days stood out. The average toll of road deaths was higher on Independence Day, July 4, than on any other day of the year across the whole study period. Alcohol tended to be involved in a higher proportion of the Independence Day deaths than on other days.
New Year's day racked up the highest number of pedestrian deaths from car crashes and ranked fifth for the highest number of daily deaths, overall. Again, alcohol consumption proved an important factor. Half of all the deaths on this day occurred between midnight and 6 am.
More deaths occurred on Saturday than any other day of the week and the peak time for fatalities was between 5 and 6 pm.
A second study in the journal assessed the numbers of children under the age of 5 who died in parked cars as a result of heat. Between 1995 and 2002, 171 deaths were recorded in this age group.
Around one in four of the children had managed to climb into an unlocked car by themselves, but almost three quarters of the children had been left in a car by adults.
One in four of the adults were aware that they had left a child in a car, but half either did not realise, or simply forgot, that they had done so.
Almost half of the children were being looked after by an adult as part of childcare. Of these 54 children, 32 had been left by family members who planned to take them to childcare, but forgot and went to work instead. The remainder were left in vehicles by childcare providers or drivers.
Journal
Injury Prevention