New York City has just finished planting 1 million new trees within an eight-year time frame. The MillionTreesNYC campaign was launched eight years ago by former Mayor Bloomberg and Bette Midler. The singer and actress runs the nonprofit New York Restoration Project, which helps revitalize green spaces in low-income neighborhoods. Together they started the effort to make New York greener by planting one million trees, and they succeeded, two years ahead of schedule. Cities like Boston, Los Angeles and Denver are trying to do the same. And it makes a lot of sense. Research shows that trees in cities make people happier and healthier.