The fourth Road to SF volume supplements the second and third, including authors and famous stories omitted from those volumes.
These anthologies are rarities as being, aside from the Science Fiction Hall of Fame volumes, among the very few that have ever been reissued by later publishers. Volumes three and four were reissued by White Wolf, in trade paperback editions, in 1996 and 1997. Gunn produced two new volumes for White Wolf in 1998, volume five covering British SF, and volume six covering non-English language sf (in translation). Then volumes one through four were issued by Scarecrow Press in 2002 and 2003. None of these later editions, however, are still in print.