For Black Americans, car travel offered freedom from segregated trains and buses, but it carried danger. Many hotels and restaurants refused Black customers, gas stations might refuse service, and sundown towns threatened people who stayed after dark. The Green Book helped drivers plan routes and stops so they would not be stranded or harmed.
Green started with listings in the New York area and expanded to cover the whole country and some international destinations. He drew on postal workers and readers to gather listings. The guide carried the line that there would be a day when it would no longer be needed.
The Civil Rights Act of 1964 banned discrimination in public accommodations, and the guide stopped publishing a few years later. The Green Book is now studied as a record of Black travel and entrepreneurship under Jim Crow. The 2018 film Green Book drew criticism for centering a white character rather than the guide's history.