York's Journal is intriguing partially for what it is NOT. The novel assumes that the reader is informed about the expedition or is able to look things up. So, as other readers have noted, it does not spread itself thin trying to cover non-fiction matters commonly available. One hardly senses, for example, the enormity of the distances and time (and drudgery) involved. Nor the trip's logistics, goals, funding, setbacks, and even its historical impact. And since its protagonist is something of a stoic, it doesn't dwell very long on privation, loneliness, and hardship.
Rather, York's Journal: A Novel is a fully imagined and unexpected trip into a trip. The language is magical; the locutions, vocabulary, and rhythms carry the reader back to our young nation's growth spurt and lend a compelling sense of authenticity. York gives us dark views of the leaders, esp. Captain Clark. Since York is Clark's black slave, his special position vis-?-vis his "master," his white company and the very different Indian nations they meet makes for some startling possibilities (and also some humorous and uninhibited sexual encounters). It offers York's troubling, mysterious dreams and nightmares as he becomes more and more alive.
Most important, though, is how the novel artfully explores powerful connections between writing, freedom and selfhood.
As a history reader and teacher, I am acutely aware that history is about "selection" of the available data. In this way many stories, often those of women and people of color are left out.
Nichols has done an amazing job of recapturing Clark's slave York's story from the Lewis and Clark Journals, never overstepping into flights of fancy but instead imaginatively giving us another insight into that incredible troop of explorers and their incredible journey. Good scholarship, excellent writing, a great read.