Traffic crashes cost the US state of Michigan $9.1bn in 2009, higher than the cost of crime, which stood at $4.7bn, according to a study by the University of Michigan Transportation Research Institute.

The report, which was funded by the Michigan Office of Highway Safety Planning, found that the cost of traffic crashes fell by 27% between 2004 and 2009, traffic fatalities declined by 25% and injuries decreased by 29%.

Crashes in Wayne County cost $1.7bn, in Oakland County they cost $877m and in Macomb County they cost $600m. Crime costs in the respective counties were $2.4bn, $260m and $209m.

In Michigan, 871 people died as a result of traffic crashes in 2009, while 579 were murdered, the report revealed.

The National Highway Traffic Safety Administration estimated that in 2000, traffic crashes cost $230bn and they remain the main cause of death for people aged between five and 33 years, despite declining fatalities in recent years.