For over three years, researchers at both Northeastern and Harvard examined tweets (September 2006 to August 2009) to see if they would be able to gauge the emotional pulse of America. The result: is this infographic titled, "Pulse of the Nation: U.S. Mood Throughout the Day Inferred from Twitter."
Knowing they could rely on users for wild mood swings and emotionally charged rants/raves packed into 140-character outbursts, they looked for certain words that indicated a person's mood and combined that data with information from the U.S. Census Bureau, the Google Maps API and other resources.
According to the researchers:
In the video, green corresponds to a happy mood and red corresponds to a grumpier state of mind. The area of each state is scaled according to the number of tweets originating in that state.
Note how the East Coast is consistently 3 hours ahead of the West Coast, so when we're sleeping in Boston, the Californians are tweeting away. It's also interesting that better weather seems to make you happier (or rather, that better weather is correlated with happier tweets): Florida and California seems to be consistently in a better mood than the remaining US.
Also note how New Mexico and Delaware behave very differently from their neighbors. Full results, individual maps, and a high-res poster can be found on the dedicated Twitter Mood website.
The time-lapse video shows mood variations throughout the day. In summary: We're happy in the morning (hopes and dreams abound), then not happy (hopes and dreams crushed under weight of reality/freeway traffic), then happy again (crushed hopes and dreams forgotten during happy hour).
And because "I'm happy" and "I'm less happy" don't always capture an individual's emotional state, researchers used this 49-page manual: "Affective Norms for English Words."
It rates emotion expressed by words. For example, "kitten" and "snuggle" are happier words than "syphilis" and "terrorist."