Postwar US labour market data reveal a significant secular decline in the employment and wage gaps between men and women. This column quantifies the implications of this shift for the US macroeconomy. Using a time series model that maps empirical trends in data onto underlying structural forces, the authors find that gender-specific labour market trends are responsible for a sizable share of the overall trend increase in GDP and labour productivity in the 1970s, 1980s, and 1990s, as well as the slowdown in GDP growth over the last 20 years.