Top Baby Names in Illinois, 1940s — Most Popular Boys & Girls Names

What the Data Says About the 1940s in Illinois

During the 1940s (1940–1949), the Social Security Administration recorded 985,145 births across the top 50 boy and top 50 girl names in Illinois. The decade's leading boy name was Robert with 45,486 births, while Mary was the top girl name with 32,973 births. The top 50 boys in this decade collectively accounted for 546,345 births versus 438,800 for the top 50 girls — a common SSA pattern in which the boy-name pool is more concentrated among fewer high-frequency choices. These totals represent only names appearing five or more times per year in Illinois; rarer names fall below the SSA's privacy-disclosure threshold and are excluded.

The 1940s sits within a specific cultural window of U.S. naming history. Pre-1950 decades like the 1940s were characterized by strong traditional and biblical naming conventions, with a small cluster of dominant names (John, William, Mary, Elizabeth) capturing a disproportionate share of births. Robert and Mary leading Illinois during this window reflects how regional preferences interact with broader national trends.

Decade totals are computed by summing SSA state-year records for Illinois across all ten years of the 1940s. Because the SSA suppresses any name with fewer than five annual occurrences in a state, the true number of unique names given in Illinois during this decade is larger than what this page lists. The dataset also treats every spelling as a separate name — for example, Kayla and Kaylah are tracked independently — so combined-spelling totals would shift the rankings somewhat. This page is provided for informational and research purposes and does not constitute naming, legal, or genealogical advice.