At one time, the U.S. Federal Census included a mortality schedule enumerating the individuals who had died in the previous year. These documents exist for the years 1850 through 1880. Although many of the original documents reside in various archives, a good number have been microfilmed and are available through NARA – and now of course, the Family History Library.
Ancestry.com has digitized the documents that have previously just been available on microfilm, now making them available online at the Ancestry.com website. These documents are indexed, allowing you to search the entire database in one search.
Keep in mind that the “census year” began on June 1, so the mortality schedules which we can access dealt with deaths taking place during the 4 years of June 1 1849 through May 31, 1850; June 1, 1859 through May 31, 1860; June 1, 1869 through May 31, 1870, and June 1, 1879 through May 31, 1880. These documents are available to Ancestry.com subscribers.