After the success of The Johnstown Flood, two new publishers offered him contracts, one to write about the Great Chicago Fire and another about the San Francisco earthquake. Simon & Schuster, publisher of his first book, also offered McCullough a contract to write a second book. Trying not to become "Bad News McCullough", he decided to write about a subject showing "people were not always foolish and inept or irresponsible." He remembered the words of his Yale teacher: "[Thornton] Wilder said he got the idea for a book or a play when he wanted to learn about something. Then, he'd check to see if anybody had already done it, and if they hadn't, he'd do it." McCullough decided to write a history of the Brooklyn Bridge, which he had walked across many times.  To me history ought to be a source of pleasure. It isn't just part of our civic responsibility. To me it's an enlargement of the experience of being alive, just the way literature or art or music is.  - David McCullough  He also proposed, from a suggestion by his editor, a work about the Panama Canal; both were accepted by the publisher. Critics hailed The Great Bridge (1972) as "the definitive book on the event."  Five years later, The Path Between the Seas: The Creation of the Panama Canal was released, gaining McCullough widespread recognition. The book won the National Book Award in History, the Samuel Eliot Morison Award, the Francis Parkman Prize, and the Cornelius Ryan Award. Later in 1977, McCullough travelled to the White House to advise Jimmy Carter and the United States Senate on the Torrijos-Carter Treaties, which would give Panama control of the Canal. Carter later said that the treaties, which were agreed upon to hand over ownership of the Canal to Panama, would not have passed had it not been for the book.

Answer this question "was it always up hill or did he have some bad spots" by extracting the answer from the text above.
After the success of The Johnstown Flood, two new publishers offered him contracts, one to write about the Great Chicago Fire and another about the San Francisco earthquake.