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It's a statistic that shows less traffic congestion sometimes can be a bad thing.

The Salt Lake City metro area has a somewhat higher-than-average rate of car deaths among the nation's top 50 metro areas — 8.4 deaths per 100,000 residents in 2009, compared with an average of 8.2, according to a Centers for Disease Control and Prevention study released Wednesday. Salt Lake City ranks No. 25 among those 50 metro areas.

Local officials say the most likely reason for Salt Lake's high rate is that it has less traffic congestion than many other metro areas — so cars travel faster, and that extra speed contributes to accidents that are more deadly than slow-speed crashes.

"We complain about congestion here anyway, but our travel times and speeds are a lot faster than in many other areas," said Robert Hull, director of traffic and safety for the Utah Department of Transportation.

For example, some places famous for traffic jams have the lowest death rates among metro areas, including 4.4 deaths per 100,000 people in Cleveland; 5.0 in Boston; and 5.1 in New York City.

"The metro areas on the East coast are heavily urbanized. Most of the time, those roadways are more congested. The speeds they are travelling are slower … and therefore crashes are usually less deadly," Hull said.

The new study also notes that traffic death rates are much higher outside of metro areas — 11.1 per 100,000 nationally, compared to 8.2 in metro areas. Hull said that again is likely because roads outside congested metro areas have higher speeds.

One limitation of the study is it looked at the residence of victims, instead of where accidents actually occurred. Hull said he would bet that many Salt Lakers killed were actually traveling outside the metro area on faster highways as part of trips to nearby recreation areas.

Even though the Salt Lake area is a bit above average for deaths among metro areas, Hull said fatalities in Utah have been steadily decreasing since 2000. The state had 240 fatalities in 2011, the lowest since 1974 — and the population is much larger now. So far in 2012, Utah has had 103 fatalities.

Hull credits that decrease to many factors, from improved safety of cars to UDOT making roads safer, better traffic law enforcement and the state's Zero Fatalities program to educate drivers about the most common causes of traffic deaths such as not wearing seat belts, speeding, drunken driving, distracted driving and aggressive driving.

The study noted that in 2009, 34,485 car-crash deaths were reported in the nation — and 22 percent of victims were between the ages of 15 and 24. Crashes were the leading cause of death for that age group.

The study said the wide variation in rates among metro areas suggests "a need to better understand how urban development patterns might relate to motor vehicle crash deaths and to identify and implement effective strategies to reduce" them.