In this paper we model U.S. labor supply and demand over the next 25 years. Despite the anticipated aging of the population, moderate population growth will provide growing supplies of labor well into the 21st century. Improvements in labor quality due to greater education and experience will also continue for some time, but will eventually disappear. Productivity growth for the U.S. economy will be below long-term historical averages, but labor-using technical change will be a stimulus to the growth of labor demand. Year-to-year changes in economic activity will be primarily the consequence of capital accumulation. However, the driving forces of economic growth over the long term will be demography and technology.