International patterns of union membership

This paper examines changes in unionization that have occurred over the last decade or so using individual level micro data on many countries, with particular emphasis on the United Kingdom, the United States and Canada. I document an empirical regularity not hitherto identified, namely the probability of being unionized follows an inverted U-shaped pattern in age, maximizing in the mid-to late 40s in 34 of the 38 countries I study. I consider the question of why union membership seems to follow a similar inverted U-shape pattern in age across countries with such diverse industrial relations systems. I find evidence that this arises in part because of cohort effects, but even when cohort effects are removed a U-shape remains. 1