FORT COLLINS - Fort Collins is ranked as one of the happiest cities in America based on how we tweet.

Researchers from the University of Vermont analyzed 10 million tweets from across the country - posts sent via Twitter - to conclude that Napa, Calif., was the happiest place in the country. The analysis looked for the frequency of "happy" words like rainbow, and for "unhappy" words like earthquake. On the state level, Hawaii was the happiest, while Louisiana was the saddest.

Fort Collins ranked 13th on the list of cities in the contiguous United States, behind Longmont (2nd), Lafayette (9th) and Boulder (12th).

The analysis also examined the use of phrases such as "LOL" and profanity. Twitter messages are limited to 140 characters, and the service is frequently used for personal status updates.

"The rich variety of happy words occurring in Hawaii paints a convincing picture of it as a happy state..." researchers said. "Louisiana is revealed as the saddest state primarily as a result of an abundance of profanity relative to the other states."