In 2005, 2 percent of the coterminous United States, some forty million acres of land, was lawn. Nearly every bit was "industrial lawn," composed of only a few nonnative grass species. These invaders are regularly mowed to a low, even height and kept continuously green and free of weeds and pests. To maintain this sea of grass Americans annually spend $30 billion. The use eight hundred million gallons of gas, seven billion gallons of water, three million tons of nitrogen fertilizer, and thirty thousand tons of pesticide. The use of pesticides alone is ten times greater than used by the average farmer and includes chemicals that disrupt normal hormone function and reproduction, are suspected to cause cancer, and are banned in other countries. Simply filling up gas-powered lawnmowers is an ecological disaster of the highest order; seventeen million gallons of gas are spilled annually. That amount is more than was spilled by the Exxon Valdez in 1989 and every twelve years would equal the amount spewed into the Gulf of Mexico during the 2010 Deepwater Horizon disaster.John M. Marzluff, Welcome to Subirdia: Sharing Our Neighborhoods with Wrens, Robins, Woodpeckers, and Other Wildlife (New Haven: Yale Univ. Press, 2014), pp. 182-83.