[영문]Despite robust growth in real GDP per capita in the last three decades, U.S. poverty rates have changed very little. We summarize some basic facts about poverty in the United States, relying on a combination of previously published data from the Census Bureau and our own tabulations based on Current Population Survey data. We then discuss and evaluate four determinants of changes in the poverty rate that have been advanced in the literature: the impact of labor market opportunities; the role of changes in family structure; the role played by government antipoverty programs; and the role of immigration.