New York is set to become the first state to require schools to regularly test their water for lead. But it's far from the only place with the problem.
The nation's driest city wants to market its water-saving efforts to the rest of the world.
The state is working toward becoming the first to get 100 percent of its energy from renewable sources. Getting there won’t be easy.
A new tool could help cities test whether (and how much) specific energy policies can slow global warming.