Most states publish life expectancy tables to be used for specified legal purposes as part of their codified statutes. You can generally find the tables by looking in the index under "Life Expectancy."
Basic U.S. life expectancy tables are posted free by the National Center for Health Statistics (www.cdc.gov/nchs/fastats/lifexpec.htm). More extensive data is published in Hugh Richards' Life & Worklife Expectancies (Lawyers and Judges Publishing). For additional sources of current and historical life expectancy data, see "Vital Statistics."