Gantos plays with a couple of meanings of "dead end" in the book's title.
Remember how the story takes place in a small, sleepy town? Well, the first meaning of Dead End refers to the fact that Norvelt is literally—um, actually figuratively—a dead end. It doesn't lead anyone anywhere. Jack's dad explicitly calls the town a "dead end" (4.47), and nothing seems to happen. And worse: the town's economy is dying. There are no jobs, and people are moving away to seek opportunities in bigger cities, which just makes the whole no-jobs situation worse.
The other meaning is more literal, and gruesome: Dead End, meaning that several nice old women (and one mean, tattooed Hells Angel) literally meet their ends in Norvelt. Because they're dead. From poison.