The structure of The Great Fire is Murphy's trademark blend of text and illustrations, including numerous photographs, drawings, and engravings from the era. In The Great Fire, the illustrations help to illuminate his subject. For example, photographs that show the O'Learys' home are invaluable to his descriptions—in the case of the O'Learys' house, the photographs support his declaration that it was a large, sturdy structure.

The text is a combination of written accounts of the Great Fire and Murphy's narration and explanation of the events. The excerpts from diaries are especially typical of Murphy's historical writings and of American-style histories in general; they provide a firsthand realism that shows that the events, however great they may be, have their greatest importance in their effect on individual people. The use of diaries and other firsthand accounts also creates an immersive text—that is, events...