Since 2004, Green Roofs for Healthy Cities has surveyed the growth of green roof installations across North America. In 2006, the industry grew more than 24 percent, and Chicago and Washington, D.C. top the list for most total square feet of green roofs installed. The authors conclude that the green roof industry is off to a very strong start and this data provides an important baseline from which to measure future progress. The also expect much greater increases in industry growth and coverage in the years ahead, particularly as more public agencies begin to invest in this important new infrastructure. Green Roofs for Healthy Cities North America Inc. is a not-for-profit membership-based industry association whose mission is to further the development of the green roof infrastructure industry.