In the absence of an American epic, we have Westerns. If Westerns were no more than shoot-outs and lonely riders, their appeal would be far less; but the good ones are less about the action, and more about the evocation of the American spirit, the nature of man, and the ideals that make the West so much different a place than the East.
The action's good, too. What kid growing up in the U.S. didn't pretend they were a cowboy, or a gunslinger, or an Indian captive at some point? So what if our imaginations weren't consistent with reality—the novels and movies told us there was a cowboy code, and we adhered to it with as much passion as any of Zane Grey's lonely heroes.
Westerns aren't just another genre to be relegated to specific shelves in the library, either. While many treat them that way, they have a long and respected literary history. James Fenimore Cooper's Leatherstocking Tales were essentially the first Westerns, while The Virginian by Owen Wister is considered literary fiction even though its main characters are cowboys and the novel features the first walk-down gun duel in literature.
Another term for Westerns might be "frontier fiction," though stories about cowboys and outlaws are typically much different than stories about wagon trains and pioneers (the Little House books are not Westerns). Yet stories about the American West are as much stories about the taming of the land, independence, the move away from civilization, and how law comes to lawless places, as they are stories about shootouts, cattle drives, and dust-smeared faces at the end of a long trail.
Don't read most of these hoping to get a history lesson. Read them for enjoyment first, and second as celebrations of the American spirit, the taming of untamed men, and as celebrations of the United States landscape. The picture you'll get of cowboys and their culture is fairly romanticized, but after all, that's part of the American dream, too.