Identifying matrilineal kin networks in the United States 1900–1940

National-level analysis of historical women's life courses and kinship networks is understudied due to data limitations. Previous analysis of patrilineal kin propinquity in the United States relied on surnames to identify the probability of non-random isonymy (same surname) as a proxy for nearby kin. One limitation of this approach is losing matrilineal kinship networks due to women's changing surnames upon marriage. Using linked census data from IPUMS MLP, LIFE-M, and Census Tree for 1900-1940, this project aims to identify birth surnames for married women to better measure matrilineal kinship networks in the United States. Results using linked census suggest non-coresidential matrilineal kinship networks underwent a similar decline as proximate patrilineal kinship networks in this time period, but nuances suggest that we should not treat these declines similarly. Matrilineal and patrilineal kin propinquity differed in the life course patterns for currently married women, and accounting for both matrilineal and patrilineal kin propinquity are important to assess the full kinship network. The rates differ in some cases between the three linked datasets, suggesting that underlying biases in the data explain some of the differences. However, the trends are similar in all geographies and methods suggesting that the identified trends are not due to random chance. While this analysis does not directly identify kin, the data produced here allows other research to identify relations from other censuses with data quality flags indicating how relationships are determined. This marks a revolutionary improvement in national-level analyses for women's life course research in the early twentieth century.