Pulse of the Nation shows the U.S. Mood Throughout the Day inferred from Twitter comments. For more details info go here.
A number of interesting trends can be observed in the data. First, overall daily variations can be seen (first graph), with the early morning and late evening having the highest level of happy tweets. Second, geographic variations can be observed (second graph), with the west coast showing happier tweets in a pattern that is consistently three hours behind the east coast.
About the Data and Visualization
The plots were calculated using over 300 million tweets (Sep 2006 – Aug 2009) collected by MPI-SWS researchers, represented as density-preserving cartograms. This visualization includes both weekdays and weekends; in the future, will we create seperate maps for each. The mood of each tweet was inferred using ANEW word list  using the same basic methodology as previous work . County area data were taken from the U.S. Census Bureau, and the base U.S. map was taken from Wikimedia Commons. User locations were inferred using the Google Maps API, and mapped into counties using PostGIS and U.S. county maps from the U.S. National Atlas. Mood colors were selected using Color Brewer 2.