Worldwide, colorectal carcinoma (CRC) varies by race-ethnicity. The highest incidence occurs in whites of European descent. Rates in blacks of South Africa are much lower, but rise with migration to westernized countries, i.e. African Americans (blacks) in the US. In the US, CRC age-specific incidence rates increased dramatically with biologic aging for black and white men and women. For all ages, rates were slightly higher for black than for whites. Among whites, overall annual rates peaked in the 1980s then declined. Stage- and subsite-specific rate shifts suggested earlier detection of cancers through screening, particularly in the distal colon. Blacks have not experienced the same stage- and subsite temporal shifts, which were observed in whites. CRC racial differences have been attributed to biologic and/or non-biologic factors as well as to routine screening patterns. Racial variations demonstrate the need for a more comprehensive understanding of colorectal carcinogenesis, epidemiology, and colorectal screening patterns for low- and high-risk populations.