Motor-vehicle deaths have increased nationwide for the second year in a row, renewing concern among safety experts and transportation officials over distracted and drunken driving.

In Colorado, traffic deaths were up in 2016 to at least 606 from 547 the previous year. The number of fatal crashes, meanwhile, was up to 556 from 507.

The numbers are small in Summit County but nonetheless reflect the trend: There were eight deaths from six crashes in the county in 2016 compared with only two fatal crashes the previous year, according to the Colorado State Patrol.

A major part of the increase is simply related to a healthy economy and persistently low gas prices, experts and officials said.

“There’s definitely a correlation between the economy and traffic deaths,” said Kara Macek, a spokeswoman for the Governors Highway Safety Association, a nonprofit that represents state highway safety offices. “We know that when gas prices go down and the economy is strong, people have more disposable income, so they drive more and take more trips.”

For many on the Front Range and around the country, those trips take them to the ski slopes and trails of Summit. Visitor volumes to the county were up last year by multiple metrics, including lodging numbers and traffic counts.

“Everything is up this year from the last: Traffic stops are up, tickets are up, crashes and fatalities are up,” said Colin Remillard, spokesman for the CSP Frisco troop. “The economy and Summit being a tourist area has a lot to do with it.”

The frequency of festivals and events in the county also plays into this dynamic. When people have more disposable income, they’re more likely to attend festivals and special events — and Summit has plenty.

Concerts and the like can contribute to drunk driving, a perennial culprit in traffic fatalities and the biggest reduction target for law enforcement.

“It’s not just more trips but the types of trips people are taking, things like events, festivals, concerts,” said Macek.

That means higher traffic coupled with higher likelihood of impairment, Macek said, creating “a kind of negative feedback loop.”

The Colorado Department of Transportation and CSP have made DUI enforcement a top priority for reigning in fatal crashes, which have crept up steadily since 2013.

In the past two years, half of the fatal crashes in Summit involved impaired drivers, according to CSP.

CDOT provides grant funding to law enforcement agencies across the state for high-visibility DUI enforcement, intended as shows of force that discourage impaired drivers from taking the risk.

Those patrols typically happen during the holidays. The most recent, over Super Bowl weekend, led to 273 arrests, including three in Summit, according to CDOT data.

“We’re trying to be more targeted with our DUIs,” said Remillard. “Most are on Highway 9, which we associate with Breckenridge. That’s where we’re hitting it hard because that’s where we’re getting them.”

Over last year’s holiday season from November to New Year’s Day, when DUIs are more common, Breckenridge was the only law enforcement jurisdiction in the county where DUI arrests had increased from the previous year.

Police chief Dennis McLaughlin cited record visitor numbers and more special events as possible factors.

At the policy level, lawmakers are focused on combating distracted driving. A bill under consideration in the state senate would increase the fine for texting and driving to $300 and four points against the violator’s license, up from the current penalty of $50 and one point.

In 2016, CSP pulled over 1,471 vehicles for violating the law, Colorado Politics reported. It applies to anyone using a phone to send text messages or engage in “other similar forms of manual data entry or transmission.”

Macek said that while it’s always encouraging to see lawmakers address distracted driving, broader bans on using handheld devices altogether are more effective and easier to enforce. Fourteen states currently have such laws.

People now use their phones for far more than texting, Macek said, and limiting laws to certain types of activities makes them harder for police to enforce.

“It’s challenging to enact tougher laws because everyone does it and it’s socially acceptable. We’ve made drunk driving socially unacceptable and the laws are very tough, but with distracted driving it’s difficult on many levels.”