The first state to pass the program was Illinois in 1911, and by 1931, all but four states had passed a program to aid mothers with dependent children. Mothers in need of pensions applied for them at the county-level. At present, 80,000 individual case files have been collected. For some states, the full universe of counties that provided MP benefits have been collected if found, while for others only a subset of counties have been found—but if a county has records, the universe of records has been collected by the research team.
Records have been collected for the following 14 states: Colorado, Connecticut, Idaho, Illinois, Iowa, Minnesota, Montana, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Washington and Wisconsin. In some states, all or nearly all records are no longer extant due to short retention schedules set by states or privacy restrictions.