Since the 1965 Immigration and Nationality Act, an increased number of foreign-born individuals have been renewing the U.S. labor force and countering population aging. While immigration is currently slowing down, the second-generation children of immigrants are reaching prime working age in growing numbers. In this study, we use the Current Population Survey to document demographic trends from 2000-25 and quantify the impact of second-generation immigrants on the labor force. We show that the second-generation population aged 25-64 has doubled since the turn of the century, accounting for more than half of the labor force growth in three out of five largest states. The median age of the population has declined by five years over this period, even as it has increased for the first- and third+ generations. Although we observe many subgroup differences that echo well-documented patterns of stratification within immigrants, we also show that the working-age second-generation are overall demonstrating strong socioeconomic and health outcomes. Together with their rising population share, the second-generation has already played an important role in countering a decline in the overall labor force participation rate and driving improvement in population health.