| List of Figures | | | ii |
| Plates | | | iii |
| Preface | | | v |
| Chapter | | | | |
| I. | The Development of the Oregon Trail as a National Highway | | 1 |
| II. | The Significance of the Trail | | 28 |
| III. | The Relation of the Trail to its Natural Environment: I. In the Loess Region | | 55 |
| | Jefferson County | 59 | |
| | Thayer County | 67 | |
| | Nuckolls County | 75 | |
| | Clay County | 82 | |
| | Adams County | 86 | |
| IV. | The Relation of the Trail to its Natural Environment: II. In the Platte Valley | | 96 |
| | Lowland Trail | 100 | |
| | Terrace Trail | 112 | |
| | The South Platte Crossing | 132 | |
| V. | The Relation of the Trail to its Natural Environment: III. In the North Platte Valley | | 137 |
| | In the North Platte Valley | 146 | |
| | Morrill County | 151 | |
| | Scotts Bluff County | 157 | |
| VI. | Resume | | 167 |
| Bibliography | | | 175 |