IPUMS USA (originally, the "Integrated Public Use Microdata Series") is a website and database providing access to over sixty integrated, high-precision samples of the American population drawn from sixteen federal censuses, from the American Community Surveys of 2000-present, and from the Puerto Rican Community Surveys of 2005-present. Some of these samples have existed for years, and others were created specifically for the IPUMS USA database. These samples collectively constitute our richest source of quantitative information on long-term changes in the American population. However, because different investigators created these samples at different times, they employed a wide variety of record layouts, coding schemes, and documentation. This had complicated efforts to use them to study change over time. IPUMS USA, like other IPUMS projects, assigns uniform codes across all the samples and brings relevant documentation into a coherent form to facilitate analysis of social and economic change. Read more about IPUMS USA