The book is a biographical portrait of photographer and inventor Eadweard Muybridge, a history of the development of technological change in the West during the later half of the nineteenth century that led to development of the modern film industry in Hollywood and later the information technology industry in Silicon Valley, and an essay focusing on a series of connections between Muybridge's life and the changing human landscape of the American West.

[1] Muybridge's life story itself seems to hinge on three major crises: his carriage accident, his murder of his wife's lover, and his break with patron Leland Stanford.

In 11 chapters, Solnit examines how the telegraph, the railroad, photography, and the science of geology all changed how humans understood time and situates Muybridge's role in history and his technological innovations within this context.

River of Shadows received a positive response from critics, including Jim Lewis of The New York Times,[3] who called the book "deeply intelligent".

[6] In Solnit's 2008 essay Men who explain things, included in her 2014 collection of essays on feminism Men Explain Things to Me, Solnit references the publication of River of Shadows and the New York Times review in an anecdote she recounts about her interactions with a male guest at a party.