Examines longevity in office of superintendents in 292 school districts, using 1975-99 data from random national sample and all school districts in North Carolina. Finds that superintendent tenure has not changed significantly since 1975-79, averaging 6-7 years over entire period. Longevity is significantly related to such factors as school board involvement in management and district poverty level. (Contains 20 references.) (Authors/PKP)