Stacked area chart showing the number of union members by nativity from 1994 to 2025. Light teal represents US-born workers and dark teal represents foreign-born workers. Total union membership declines modestly over time, driven largely by a reduction in US-born union members. In contrast, the number of foreign-born union members gradually increases, rising from roughly 1.3 million in the mid-1990s to just over 2 million by 2025. As a result, foreign-born workers account for a growing share of total union membership despite overall membership decline.