Victor Hugo Green, publisher of The Negro Motorist Green Book, was a visionary.

Green envisioned a network of safe and welcoming places for African Americans. First published in 1936, the travel guide targeted the New York City metropolitan area. By 1938, the Green Book included all the states east of the Mississippi River.

Over time, there were 9,500 Green Book listings across the United States, Canada, the Caribbean, Mexico, South America, Europe and Africa. The highest concentration was in cities with large African American populations including Atlantic City, Washington, DC, Atlanta, Chicago and Philadelphia.

Check out this WHYY podcast focusing on Philadelphia’s extant Green Book sites, “Philly’s ‘20th century Underground Railroad’ hides in plain sight.”