The non-profit organizations, or social service agencies, are very present in the USA. This is a big part of the american culture : one in four citizen is a volunteer in, at least, one association.
This trend appears from the birth of the American republic. The sociologists see two reasons for this phenomenon : on the one hand, the absence of an official religion in US has pushed congregations into a competition for social actions. On the other hand, the low investment of the national state in the public domain has pushed citizens to act for themselves.
In 1830, Tocqueville, a french politician precursor of sociology, is impressed by this phenomenon while he is traveling in the United States. He sees it as a natural defense against individualism. According to him, thanks to the associations, the population learns to think in group, and this «school of democracy» protects them from a too strong influence of the State.
The US government has, of course, always encouraged associations. George Bush Sr. spoke of the «thousand bright spots» of American goodwill. For his part, Bill Clinton has further limited social programs to transfer them to charities, mostly religious. Anyway, if the US refuses to be a «welfare state», it is yet the country in the world that pays the largest budget to the non-profit sector. Associations are also funded by private donations exempt from taxes.
Today, this culture is changing. The associative world, the NGOs, the public interventions and the companies investing in the social field mix all together and make the all thing more difficult to understand. On the one hand, there are professional groups, managed by employees, and on the other, more one-time voluntary work. This last practice contradicts Tocqueville : when the good will is limited to disparates actions, it does not allows to learn the principle of collective decisions.
Check more about the non-profit industrial complex