The Decennial Census Digitization and Linkage project (DCDL) is an initiative to produce linked restricted microdata files from the decennial censuses of 1960 through 1990. This paper provides background on the decennial census files and the previous work leading to the DCDL project. The proposed work plan is described in detail, as well as the dissemination strategy for the resulting linked data. When combined with existing linkages between the censuses of 1940, 2000, 2010, the soon-to-be public 1950 census, and the future 2020 census, the DCDL project will provide the final component in a longitudinal data infrastructure that covers most of the U.S. population since 1940.