Despite more trucks on the roads, the likelihood of being in a fatal collision with a commercial vehicle has declined steadily since 1975 in the United States. However, the number of people dying in truck-related road accidents has hovered around the 5,000 mark, according to the Department of Transportation.

At the same time, the fatal crash rate for truck-related accidents has shrunk dramatically. In 1975, 4,483 people died, and the fatality rate was 4.6 deaths for each 100 million vehicle miles traveled. The rate was 2.4 for each 100 million in 1997, the most recent year for which statistics are available. Among the 5,398 highway deaths recorded two years ago were 717 occupants of large trucks, those with a gross vehicle weight rating of 10,000 pounds or more.

In 1997, the more than 7 million registered large trucks coursing through the nation’s arteries accounted for just 3.7% of the vehicles involved in traffic accidents, with the two top categories being passengers cars at 66.5% and light trucks at 28.7%, according to DOT reports.

Trucking prefers to look at the miles-traveled statistic to determine the fatality rate involving commercial vehicles and to illustrate that drivers are less prone to deadly accidents than in the past. Critics like to use the raw numbers on truck-related road deaths as their benchmark to show things are not as rosy as the industry claims.

The issue came into the public eye last spring when Congress questioned why the number of deaths increased over the past three years while the fatality rate had declined slightly.

“Fatalities associated with air and rail transportation have decreased, even though passenger miles increased,” Kenneth Mead, the DOT’s inspector general, told Congress last spring.

“It’s important to look at raw numbers, but it’s important to look at trends, and the trends are headed in the right direction,” Laurie Baulig, senior vice president of policy and regulatory affairs at American Trucking Associations, told the National Transportation Safety Board.