The Negro Traveler's Green Book, a guidebook for African-American travelers (also known as The Negro Motorist's Green Book), was published by New York City mailman Victor Hugo Green in response to pervasive and widespread racial discrimination during the pre Civil Rights-era. Green's guide featured hotels, restaurants, service stations and other places where African-Americans could count on being served.

The Architecture of The Negro Travelers' Green Book is a public architectural history project that studies the sites listed in The Green Book to discover their history and support their preservation. Zipf, along with partners Anne Bruder and Susan Hellman, has co-lead this project since 2016. Sponsored by the Institute for Advanced Technology in the Humanities at the University of Virginia, the database allows you to explore these sites by year, state, establishment type, and owner. Zipf, Bruder, and Hellman work with scholars across the nation to add more to this database. Please reach out if you'd like to join the effort.