According to the U.S. Census Bureau, in 2004, Miami had the third highest incidence of family incomes below the federal poverty line in the United States, making it the third poorest city in the USA, behind only Detroit, Michigan (ranked #1) and El Paso, Texas (ranked #2). Miami is also one of the very few cities where its local government went bankrupt, in 2001. However, since that time, Miami has experienced a revival: in 2008, Miami was ranked as "America's Cleanest City" according to Forbes for its year-round good air quality, vast green spaces, clean drinking water, clean streets and city-wide recycling programs. In a 2009 UBS study of 73 world cities, Miami was ranked as the richest city in the United States (of four U.S. cities included in the survey) and the world's fifth-richest city, in terms of purchasing power.

As of 2004, what city was the poorest in the United States?