The objective of this article is to review the literature and describe the current technology used by U.S. cotton gins for seed cotton unloading. Unloading systems supply the gin with raw material. Their essential functions are 1) to remove non-cotton materials such as protective covers used during transport and storage and large foreign objects such as dirt clods and rocks; 2) to break apart modules, which are compacted for transport and storage, so seed cotton is in small, loose clumps that can be dried more easily and cleaned; 3) to remove green bolls and some soil; and 4) to supply the gin with a steady, controlled flow that can be interrupted if there is a problem. Changes in the way harvested cotton is packaged in the field have resulted in significant changes in unloading systems in recent years. Current recommendations and best practices are presented.