Many descendants of freed slaves continued to work as sharecroppers and laborers after emancipation, but many migrated among the counties, moved to cities, or left the state for other opportunities. Around 1910–20, the infestation of the cotton crop by the boll weevil destroyed much of the crops and plantation system, but the lingering effects of a cotton economy remain evident. To escape lynchings and social oppression, and after the boll weevil and increased mechanization of agriculture, thousands of African Americans left Alabama to go to industrial cities of the North and Midwest in the Great Migration of the first half of the 20th century. But African Americans continue to make up the majority of the population in most rural Black Belt counties. Today the term "Black Belt" is mostly used by scholars and the media as a geologic characterization.