That study, which ranked the 100 deadliest highways in America based on fatal crash data, identified five Illinois interstates making the list. Just How Deadly Are Some Of Illinois' Roads And Highways? Another way researchers often look at it is through “fatal crashes” versus total fatalities. Illinois averages roughly 1,000 fatal crashes per year, which translates to that same ballpark of just over a thousand lives lost on the roads annually. To break that down:That’s roughly 3 to 4 traffic deaths every single day in IllinoisAnd about one fatal crash every 8-9 hours statewide