4. THE PONY RIDER BOYS IN THE OZARKS; or, The Secret of Ruby Mountain.
5. THE PONY RIDER BOYS IN THE ALKALI; or, Finding a Key to the Desert Maze.
6. THE PONY RIDER BOYS IN NEW MEXICO; or, The End of the Silver Trail.
7. THE PONY RIDER BOYS IN THE GRAND CANYON; or, The Mystery of Bright Angel Gulch.
8. THE PONY RIDER BOYS WITH THE TEXAS RANGERS; or, On the Trail of the Border Bandits.
9. THE PONY RIDER BOYS ON THE BLUE RIDGE; or, A Lucky Find in the Carolina Mountains.
10. THE PONY RIDER BOYS IN NEW ENGLAND; or, An Exciting Quest in the Maine Wilderness.
11. THE PONY RIDER BOYS IN LOUISIANA; or, Following the Game Trails in the Canebrake.
12. THE PONY RIDER BOYS IN ALASKA; or, The Gold Diggers of Taku Pass.