On January 8, 1971, President Richard M. Nixon signed into law the bill creating the Chesapeake & Ohio Canal National Historical Park. In the mid-1970s, National Park Service historian Harlan D. Unrau produced a major, handwritten, multi-volume study of the history, engineering, operation, maintenance, and other aspects of the Chesapeake & Ohio canal. A rough, unedited typed version was produced in the early 1980s for general use by park staff. In 2006, C&O Canal NHP volunteers began the task of transcribing the Unrau work into MS Word.The work represents an early compilation of the canal’s history and engineering that has never been surpassed and will be of incalculable value to researchers and those who simply desire to know more about this unique historic treasure. It should be noted that the original work was developed as sixteen chapters organized in several volumes. The first four chapters are not included here and have not yet been transcribed. For the most part those early chapters contain information on the general state of canal building and engineering in the early 19th century, and background history- although there is also a section on certain C&O structures and engineering problems. Overall, however, the information is less specific to the C&O in chapters one through four than that in chapters five through sixteen treated as separate monographs in this volume.