Plano, Texas, has some pretty ho-hum claims to fame: It’s home to junk-food headquarters Frito-Lay and the Dr. Pepper Snapple Group, for starters, as well as to retail giant J.C. Penney. But it’s also America’s safest city by our determination, and that’s nothing to yawn at.

Plano, a city of 278,000 that’s just outside Dallas, boasts the lowest violent crime rate of the cities we looked at and the sixth-lowest traffic fatality rate, putting it tops on our list for the second year in a row. The Las Vegas suburb of Henderson, Nev., and Honolulu come in second and third, respectively.

So what makes these metropolises oases of relative tranquility? Wealth is one key factor.

“One of the underlying things, in terms of a city’s safety, would be a very strong tax base, as there are a number of services that are reliant on it,” notes Scott B. Clark, president of the New York-based Risk and Insurance Management Society. “That includes an effective, well-staffed police department, fire department and school system.”

The median household income in Plano is $79,234, according to the U.S. Census Bureau, nearly 60% above the national average, and 8.1% of residents are below the poverty line, compared to a national rate of 15.1%. The city is also home to a number of Fortune 500 companies.

“Plano is a very clean, affluent suburb with no inner city per se,” says John Worrall, head of the criminology program at the University of Texas at Dallas. “Plus it has one of the few police departments in the U.S. that require four-year degrees. I don’t know that there is research to back up its making things safer, but it makes Plano unique.”

Henderson, Nev., takes the No. 2 spot despite its location within the Metropolitan Statistical Area of Las Vegas-Paradise, which ranked ninth this year on Forbes’ list of America’s Most Dangerous Cities. That may be because Henderson has a relatively high median income of $61,861, a low poverty rate (7%) and higher median home prices than Las Vegas, points out Tamara Madensen, a criminology professor at the University of Nevada in Las Vegas. Also of help, she adds, is that “casinos in Henderson cater mainly to local residents, which reduces traffic and the number of tourists moving about in the city.”

That’s an important point compared to Vegas: Since crime rates are calculated based on Census populations, violent crimes involving tourists inflate the numbers. “The number of people who visit the Strip and downtown Las Vegas each year,” over 35 million, “make it difficult to estimate the real ‘risk’ of crime for individuals living in Las Vegas. Tourist numbers are rarely factored into risk analyses,” Madensen says.

Behind the Numbers

To find America’s 10 safest cities, we looked at metropolises with populations above 250,000. We ranked them by violent crime rates—the number of violent crimes (murder, forcible rape, robbery and aggravated assault) per 100,000 residents in 2010, as reported by the Federal Bureau of Investigation.

We also ranked each city on the traffic-fatality rate per 100,000 residents based on 2009 data, the most recent available, from the National Highway Traffic Safety Administration. We then averaged the ranking for each city to arrive at final scores. In the event of ties, the city with the lower crime rate got the higher ranking.

Here are America's five safest cities:

#5 Lincoln, NE
Car fatality rank: 1
Violent crime rank: 16

Lincoln, NE is NO. 5 on the safest cities list. Photo: iStock

#4 Santa Ana, CA
Car fatality rank: 4
Violent crime rank: 11

Santa Ana, CA is No. 4 on the safest cities list. Photo: iStock

#3 Honolulu, HI
Car fatality rank: 7 Violent crime rank: 4

Honolulu, HI is No. 3 on the safest cities list. Photo: iStock

Hawaii has some of the strictest gun control laws in the nation, the city is relatively affluent and that famous relaxed aloha spirit may play a role in keeping accident and violence rates low.

#2 Henderson, NV
Car fatality rank: 5
Violent crime rank: 3

Henderson, NV is No. 2 on the safest cities list. Photo: City of Henderson/small>

The Las Vegas suburb has a low poverty rate of 7% and the casinos in the city cater mainly to locals, which "reduces traffic and the number of tourists moving about in the city," says UNLV criminologist Tamara Madensen.

#1 Plano, TX
Car fatality rank: 6
Violent crime rank: 1

Plano, TX is No. 1 on the safest cities list. Photo: Lana Sundman/Alamy

The affluent Dallas suburb has a median household income of $79,234, 60% above the national average; a police force made up of college graduates; and a strong community watch program.

Click here to see more of America's Safest Cities.