The life table series published in the United States Mortality DataBase were produced using the methods of the Human Mortality Database with some adjustments where necessary.
For a Summary of these methods, see http://www.mortality.org/File/GetDocument/Public/Docs/MP-Summary.pdf.
For the Full Protocol, see http://www.mortality.org/File/GetDocument/Public/Docs/MethodsProtocolV6.pdf.
All adjustments to the HMD Methods Protocol are described in the USMDB Documentation FileCounty Methods
Read the County Methods Protocol (.pdf) for explanation of the file format and for more details about the Bayesian model and the life table calculations. The R and Stan codes to run the Bayesian model will soon be available here, as well. We also link to the companion reference, A Flexible Bayesian Model for Estimating Subnational Mortality (Alexander, Zagheni, Barbieri, Demography 2017) (link to pdf).