In June of 1920, the Army Reorganization Act consolidated all enlisted ranks into seven pay grades. Army General Order 36 of June 19, 1920 1 specified a single title for each grade, except for the second pay grade, which was shared by first sergeants and techincal sergeants.

Timeline of U.S. Army Enlisted Ranks, 1920 to Present. The following table shows the major changes in US Army enlisted ranks and insignia from the post-World War I reorganization of the enlisted grades in 1920 to the present day.

The era from 1902 to 1920 was the most complex era for enlisted rank insigniain the United States Army. During that time the army was organized with each branch (cavalry, infantry, artillery, etc.) having its own rank structure. This led to a large number of insignia designs being used.

U.S Army enlisted rank insignia reached its greatest complexity in the First World War period. The expansion of new branches and grades caused a proliferation of insignia which taxed the army's supply system and left room for reform, which would come in the grade consolidation of 1920.