Born in Baltimore, Maryland, on April 8, 1951, Morrow grew up in Littleton, Colorado, and, "after a decade of vagabonding from Honduras to France, Italy to England", settled in New York City, where he remains. In 1966, he was selected by the Colorado Medical Association to serve with a small number of other teenage volunteers as a medical assistant with the Amigos de las Americas program, giving inoculations and working with health-care professionals in poor, very rural areas in Honduras. The following year, 1967–1968, Morrow was a foreign exchange student under the auspices of the American Field Service, completing his final year of high school at a Liceo Scientifico in Cuneo, Italy. After completing his B.A. in English Literature at the University of Colorado, Boulder, 1969–1972, where he graduated summa cum laude with a Phi Beta Kappa, he received a Danforth Fellowship to continue graduate studies in English and comparative literature at Yale University. Upon leaving Yale, Morrow moved first to Ithaca, New York, where he began research on a full-scale bibliography of Wyndham Lewis, consulting the archives at Cornell University, and then to Santa Barbara, California, where he met John Martin, of Black Sparrow Press, who would publish the bibliography in 1978.