Given the lack of information on mortality in the nineteenth century United States, it seems appropriate to apply techniques which have been created for mortality estimation for developing nations with inadequate vital registration data, to the historical American experience. Two such related sets of techniques are the Brass, Sullivan, and Trussell methods and the technique here called the Surviving Children Method, which utilizes the age structure of surviving children and the number of children ever born to women in various age or duration of marriage categories. Both techniques estimate child mortality. Coale and Demeny model life tables are used to extend child mortality estimates to adult mortality. The techniques are applied to census manuscript samples from seven New York counties in 1865 and seven Pennsylvania counties in 1900, both censuses having information on children ever born. The estimates confirm a drop in mortality between 1865 and 1900 in New York and large differentials between native and foreign-born populations as well as between rural and urban populations.