David Trowbridge is a professor of history and Director of the African and African American Studies program at Marshall University. He is the author of numerous works, including a two-volume open textbook about US history, A History of the United States. It was published by Flat World Knowledge in 2012. The book is similar to other textbooks in that it was peer-reviewed throughout its creation and is available to students in a variety of formats (print, audio, digital). The book is unique in that students can also read the book for free on the Flat World Knowledge website.