This study was conducted under the auspices of the Center for Studies in Demography and Ecology at the University of Washington. It is a nationally representative sample of the population of the United States in 1900, drawn from the manuscript returns of individuals enumerated in the 1900 United States Census. The sample is made up of 27,069 households containing a total of 100,438 individuals. This represents approximately 1/760th of the total population of the U.S., which was nearly 76,000,000 in 1900. The file contains a household record for each household selected in the sample, with variables describing the location and composition of the household. Each household record is followed by a record for each individual who resided in that household. These ''person records'' contain variables describing the demographic characteristics, nativity, education, and occupation for each person. The collection consists of two separate physical files. The first is the logical record format data file which contains 127,507 cases (27,069 household records and 100,438 individual or person records).