Brownfields are abandoned or underutilized industrial and commercial sites that are, or are perceived to be, chemically, physically, or biologically contaminated. In the early 1990s, a coalition of big-city mayors and legislators from urban industrial states pressured the US Congress and the US Environmental Protection Agency to start a pilot program that would turn these eyesores into new factories, businesses, and other job- and tax-creating activities. Housing was not an initial focus.