In the book, the two-term president discusses the Sept. 11 terrorist attacks, his decisions to send troops to Afghanistan and Iraq and the response to Hurricane Katrina.
An initial print run of 1.5 million copies has been increased to 1.85 million. E-book sales alone are 100,000.
Random House said last week that opening-day sales of "Decision Points" were its highest since former President Bill Clinton's "My Life" debuted in 2004.
