Movie S1.

For each year, we assigned colors to the states according to the method explained in SI Text, Principal Component Analysis and Hierarchical Clustering. States that share similar colors have similar distributions of the baby names. This notion of similarity comes from the PCA (details regarding this method are provided in SI Text, Principal Component Analysis and Hierarchical Clustering). Although northern and southern states belong to two distinct cultural areas during the first decades of the 20th century, a new configuration of states emerges at the end of the century, where central and coastal states (with very long range correlations covering thousands of miles of physical distance) form roughly two different cultural areas. This movie shows the results of the analysis performed on baby girl names.