National Public Radio: It’s easy in the news business to know when a big story begins. A plane crashes into a building. A levy crumbles. An explosion destroys a deep-water drilling rig. But it’s often difficult to pick the moment when the story ends. Families grieve for years. Cities rebuild slowly. Lawsuits slog through the courts. In most big disasters, the effects linger for a long time — but the news cameras don’t. Perhaps that’s why this weekend’s long-awaited news from the Gulf of …