JILL JONNES, who holds a Ph.D. in American history from Johns Hopkins University, is the author of Eiffel's Tower, Conquering Gotham, Empires of Light, and South Bronx Rising. Founder of the nonprofit Baltimore Tree Trust, she is leading the Baltimore City Forestry Board's new initiative, Baltimore's Flowering Tree Trails. As a staff member of the 2010 Presidential National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, she wrote the first chapter of the report Deep Water- The Gulf Oil Disaster and the Future of Offshore Drilling. In the fall of 2011, she was a scholar studying Trees as Green Infrastructure at the Woodrow Wilson International Center for Scholars in Washington, DC. Jonnes was also named a National Endowment for the Humanities scholar and has received several grants from the Ford Foundation. REBECCA STEFOFF has devoted her career to writing nonfiction books for young readers. Her publications include histories, literary biographies, an encyclopedia of maps, and numerous books on science and environmental issues. She has also adapted a number of landmark works in history and science, including Howard Zinn's A People's History of the United States, Jared Diamond's The Third Chimpanzee, and Charles C. Mann's bestselling 1493.