Every Tree in the City, Mapped

How many trees are in your city? It might seem like a straightforward question, but finding the answer can be a monumental task. New York City's 2015-2016 tree census, for example, took nearly two years (12,000 hours total) and more than 2,200 volunteers. Seattle's tree inventory won't be complete until at least 2024. Such efforts aren't done in vain; in the short term, they allow cities to better maintain their urban trees.