STUDY: BOULDER IS THE NATION’S “HAPPIEST” CITY

What is the key to happiness? Apparently, moving to Boulder.

Boulder was named the “happiest” city in the country in a recent study published by National Geographic.

The index — done by National Geographic, author Dan Buettner and Gallup — studied 15 metrics, including healthy eating, civic engagement, financial security and vacation time.

Boulder’s bike-friendly streets contributed to its ranking.

“There’s a high correlation between bikeability and happiness in a city,” Buettner wrote.

But he also warned: “Stress is on the rise; on average, 49 percent of locals surveyed reported feeling stress.”

The poll drew on nearly 250,000 interviews conducted with adults from 2014 to 2015 in 190 metropolitan areas.

Fort Collins ranked fifth in the survey, and Colorado Springs finished 18th.