Aside from Disneyland, the happiest place on earth appears to be Denmark (Reuters):
LONDON - If you’re looking for happiness, go and live in Denmark.
It is the happiest country in the world while Burundi in Africa is the most unhappy, according to a report by a British scientist released on Friday.
...
The main factors that affected happiness were health provision, wealth and education, according to White who said his research had produced the “first world map of happiness”.
No surprise about Burundi. Poverty (per capita GDP of US $700) and ethnic conflict (a twelve year war between the Hutu and Tutsi's) do not make for happiness, stability or anything nice. For Denmark see Alex Tabarrock's interesting post.
The US looks like an anomaly in this data set:
“Smaller countries tend to be a little happier because there is a stronger sense of collectivism and then you also have the aesthetic qualities of a country,” White said.
While we have some strong sense of shared ideals (freedom and all that) we are one of the only large, diverse countries that shows up as being even moderately happy. The trend in the rest of the world may be to move to smaller, less ethnically or racially diverse countries. Certainly the current creation of states is at least somewhat arbitrary, as Austan Goolsbee pointed out in last week's Economic Scene column in the NYT:
Straight lines are usually the sign of an arbitrary colonial mapmaker. Natural barriers like rivers and mountains seldom look tidy. Taking the measures of partitioning and neat borders, their study [Goolsbee is referrring to a study by Easterly, Alesina, and Matuszeski he referenced earlier] compares the performance of countries with natural borders to those with artificial ones and finds, overwhelmingly, that artificial nations suffer terribly -- lower income, horribly ineffective and corrupt governments, less respect for the law, low literacy, limited access to clean water, poor health care, you name it.