Overground Railroad chronicles the history of the Green Book, which was published from 1936 to 1966 and was the "Black travel guide to America." For years it was dangerous for African Americans to travel in the United States. Because of segregation, Black travelers couldn't eat, sleep, or even get gas at most white-owned businesses.

The Green Book listed hotels, restaurants, department stores, gas stations, recreational destinations, and other businesses that were safe for Black travelers. It was a resourceful and innovative solution to a horrific problem. It took courage to be listed in the Green Book, and the stories from those who took a stand against racial segregation are recorded and celebrated.

This young reader's edition of Candacy Taylor's New York Times Notable Book discusses a number of sites included in the Green Book as well as the effects of systemic racism til the present day. It includes her own photographs of Green Book sites, as well as archival photographs and interviews with people who owned and used these facilities. The book also includes an author's note, endnotes, bibliography, timeline, and index.