Marie Cusick

Regal fritillary butterflies have largely disappeared from the East Coast, save for a military base in central Pennsylvania. A few days each summer, hundreds descend for guided tours to see them.

Forty years ago, the U.S. nuclear industry suffered its worst nuclear accident. Today, the remaining reactor at Three Mile Island is slated to close because of cheaper competition from natural gas.

A Maryland dam has been helping to clean up the Chesapeake Bay by holding back sediment that can harm aquatic life. But now the dam's sediment pools have filled up earlier than projected.

Pipelines are center stage in a fight over the nation's energy future, concerns about climate change and private property rights. Donald Trump's election means the battles are likely to continue.

Driven by new regulations and fracking, more coal power plants are retiring for cheaper, cleaner-burning natural gas. But scientists have yet to work out the fossil fuel's imperfect climate footprint.

This week marks the 150th anniversary of the battle of Gettysburg. While it's widely known as the critical turning point of the Civil War, the small Pennsylvania town has seen many other battles since then — over how the historic site should be preserved and remembered.

Residents of the South End neighborhood of Albany, N.Y., had made repeated requests for a bus route for their underserved neighborhood. Resident Willie White brought his neighbors together to demand a bus route — and a seat at the table in city politics.