The District of Columbia and Massachusetts are the safest places to drive in the U.S., while West Virginia and North Dakota rank among the most dangerous, according to a new study.

The study, Road Safety in the Individual U.S. States: Current Status and Recent Changes was conducted by researcher Michael Sivak of the University of Michigan Transportation Research Institute.

Sivak based his research on data released by the National Highway Traffic Safety Administration and the Federal Highway Administration in 2012, the last year the information was available.

D.C. had 4.20 traffic deaths per billion miles driven and 2.37 per 100,000 people, while Massachusetts had 6.24 fatalities per billion miles and 5.25 per 100,000 people, according to the study.

The study showed that West Virginia was the most dangerous state overall when it comes to distance-based fatalities, with 17.63 traffic deaths per billion miles. Based on fatalities per population, North Dakota was the most dangerous at 24.30 fatalities per 100,000 people.

The District of Columbia again had the fewest fatalities (15), followed by Alaska (59) and Rhode Island (64). Texas (3,398), California (2,857) and Florida (2,424) were at the bottom of the list.

"Road fatalities in the U.S. have dropped substantially. The data for 2012 show a reduction of 22.7 percent since 2005 (NHTSA, 2007; 2014). Reductions of similar magnitudes were also achieved for fatalities per distance driven and fatalities per population," reads the study.

Areas with the largest reductions in total fatalities since 2005 were the District of Columbia (-68.8 percent), Nevada (-39.6 percent) and Mississippi (-37.5 percent).

Locations that saw the largest increases in highway deaths were North Dakota (+38.2 percent), Vermont (+5.5 percent) and Maine (+3.0 percent).

 There were a total of 33,561 traffic fatalities in the U.S. in 2012, according the NHTSA.

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