Robert Caro has published four volumes of his biographical series, "The Years of Lyndon Johnson" and is working on a fifth volume. He stated in a February 2025 interview, “Well, I’ll tell you what pages I’m up to—951,” while declining to say what he thought the total number of pages would be. Per Wikipedia, the first 4 volumes had the following page counts:
The Path to Power (1982): 882
Means of Ascent (1990): 506
Master of the Senate (2002): 1167
The Passage of Power (2012): 736
The question will be resolved based on the first paper (not e-book) edition of the fifth volume of this series, whether or not a sixth volume is published. A fifth volume published after Caro's death (e.g., with a co-author) qualifies. If no fifth volume is published, the question is n/a.