Stacked area chart showing the number of union members in the public sector by level of government from 1983 to 2025. Navy represents federal workers, light teal represents state workers, and medium blue represents local workers. Local government employees account for the largest share of public-sector union members throughout the period. State government union membership grows steadily over time, while federal union membership remains relatively stable. Total public-sector union membership peaks in the late 2000s and declines modestly thereafter.