For the third year in a row, an insurance study said South Dakota's biggest city has the safest drivers in America.

Researchers with Allstate Insurance analyzed two years of internal data to calculate the chance that drivers in 193 of the nation's largest cities would be involved in an accident.

They found that Sioux Falls, S.D., drivers average an accident once every 14.5 years. Click here to see the complete list.

"I am happy to know that our residents are continuing to drive safely, particularly with the July Fourth holiday approaching," said Dave Munson, mayor of Sioux Falls. "The quality of our community driver education programs, combined with the careful consideration of our traffic engineering department, goes a long way to make our roadways safe for everyone."

Holding on to the number two spot for the third consecutive year is Fort Collins, Colo. On average, motorists in Fort Collins experience a car collision every 13.4 years.

For the past four years, Allstate actuaries have conducted an in-depth analysis of company claim data to determine the likelihood drivers in America's 200 largest cities will experience a vehicle collision compared to the national average.

"Allstate's America's Best Driver's Report was created to boost the country's discussion on safe driving," said Mike Roche, senior vice president, Allstate's Claim Organization. "Each year, we hope that the report will increase awareness on the importance of being tolerant and attentive behind the wheel."

On the other end of the scale, the study says drivers in Washington, D.C., average a crash about once every 5.5 years.