Mark Twain ends the “Adventures of Huckleberry Finn” with these words: “And so there ain’t nothing more to write about, and I am rotten glad of it, because if I’d a knowed what a trouble that was to make a book I wouldn’t a tackled it and ain’t agoing to no more. But I reckon I got to light out for the Territory ahead of the rest, because Aunt Sally she’s going to adopt me and sivilize me and I can’t stand it. I been there before.” Until relatively recently, it was common for boys even of Huck’s age—he was 12 or 13—to “light out for the Territory,” though not in the sense Huck meant. Just a century ago, teenage males often graduated eighth grade in school and then metaphorically lit out for the territory by joining the work force, laboring on farms to help out the family, seeking adventure …