 On January 11, 2001, "Washington Post" columnist Lloyd Grove reported in his column "The Reliable Source", that a co-worker had found a "serious historical error" in the same book that "a chastened Ambrose" promised to correct in future editions.A number of journal reviews also sharply criticized the research and fact checking in the book.Reviewer Walter Nugent observed that it contained "annoying slips" such as mislabeled maps, inaccurate dates, geographical errors, and misidentified word origins, while railroad historian Don L. Hofsommer agreed that the book "confuses facts" and that "The research might best be characterized as 'once over lightly'."