SUMMARY This project will digitize and disseminate the only remaining non-digitized U.S. census records between 1790 and the present: the 1960 full-count Census. We will then use the resulting microdata to complete the largest longitudinal data infrastructure in the U.S. The linked infrastructure currently includes data from the censuses of 1940 and 2000-2020 and will soon include data from the full-count censuses of 1950, 1970, 1980, and 1990, and the 25% sample from 1960. The current project will incorporate the full-count 1960 Census. These new data will provide a new mid-life observation for the oldest Americans, including those who lived through the Depression and World War II, as well as the early-life experiences of their children who are now entering retirement. When complete, the project will provide the final piece of a massive and powerful multi-purpose resource that will enable a wide range of new discoveries and applications. We will undertake four key tasks to accomplish this goal: (1) create a full-count microdata file of the 1960 Census, (2) capture street address and assign detailed geography, (3) assign linkage keys to facilitate longitudinal analysis, and (4) document and disseminate the new cross-sectional and longitudinal data. With our addition of linked cases from 1960, population health researchers will be able to use these data to analyze the life-course trajectories of hundreds of millions of Americans over the past century. Researchers will be able to incorporate information on early and mid-life experiences—such as parental economic status, childhood environmental exposures, public policy, social institutions, neighborhood characteristics, and housing conditions—into investigations of the health, well-being, and mortality of Americans over their lives and through generations.