Actually, the strength of an economy depends on the movement of its currency. Many, many rich people move their money very effectively, but nobody can move a buck like the spend-happy lower-mid class. (I know, I'm there.
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As far as people in the lowest class who can't afford to pay rent and eat at the same time, I think that it is far past time to raise the minimum wage, split the nation into distinct regions (such as by county/parish) and set the minimum wage according to the actual cost of living... This should be done *every* year, and should be increase *at least* at the rate of inflation. With more poor people spending money, there is more money around to spend, which creates more opportunities for businesses to make a buck, which they then have to turn around and give to their employees, who spend all of their money yet again, bringing more and more liquid money into the economy, bringing stability, growth, and prosperity.
But, I suppose that's just a pipe dream... It's not like it wouldn't take more than a few months in legislative debate, then the stroke of a mature, honest president's pen to make something like this happen.