Robin Nagle: What I discovered in New York City trash

New York City residents produce 11,000 tons of garbage every day. Every day! This astonishing statistic is just one of the reasons Robin Nagle started a research project with the city's Department of Sanitation. She walked the routes, operated mechanical brooms, even drove a garbage truck herself—all so she could answer a simple-sounding but complicated question: who cleans up after us?