I define the “immigrant share” for each of these skill groups as the fraction of the workforce in that group that is foreign-born. 4 The immigrant share obviously measures the size of the supply shock that affects the labor market for a particular skill group at a particular time. Figure 1 illustrates the supply shocks experienced by selected skill groups between 1960 and 2010. It is well known that immigration into the United States greatly increased the supply of high school dropouts in recent decades. What is less well known is that this supply shift did not affect all age groups within the population of high school dropouts equally. Moreover, the nature of the imbalance changed over time. As Panel A of the figure shows, immigrants made up almost 60 percent of all high school dropouts with around 20 years of experience in 2010, but only 30 percent of those with less than five years. In 1960, however, the immigration of high school dropouts most increased the supply of the oldest workers. Similarly, Panel B shows that in 1990 the immigrant supply shift for workers with more than a college education was reasonably balanced across all experience groups, generally increasing supply by around 10 percent. By 2010, however, the supply shift for these highly educated workers was far larger for those with less than 15 years of experience.