The First Transcontinental Railroad: Central Pacific & Union Pacific

If you are only going to read one book on this subject, I'd suggest Nothing Like It In the World : The Men Who Built the Transcontinental Railroad 1863-1869 or Empire Express: Building the First Transcontinental Railroad. Galloway died in 1943, and his work has often been used as a source for the more recent books in the field, like those just mentioned. However, for anyone with a deeper interest in the subject, this is a treasure-trove of detail. Galloway was a prominent civil engineer with much railroad experience, and he brings a unique perspective to the subject.