WATERBURY, Conn.—It was the tree of choice in the eastern United States. Whole communities depended upon it. Naturalists swooned over its majesty. Farmers built their barns and fences from it. Cabinetmakers relished its honeyed smoothness. People competed with animals for its fruit.

Then in 1904, the American chestnut started to die. An Asian blight raced like wildfire from state to state, ultimately destroying as many as four billion trees, or one quarter of the region's entire hardwood population.

The American chestnut still has not recovered. For most of the past century, those "chestnuts roasting on an open fire" and eaten on a winter's night have come from Asia and Europe. An awful lot of people experts and amateurs alike are trying to change that, and Connecticut is at the center of the effort.

What makes the chestnut campaign additionally intriguing is that it strives to recreate a species that is not fully dead, just badly ailing. That offers some hope for its salvation.