Ontario and the United States share a language, a media, and a century. Do they name their children the same way? Two measures, side by side — how fast the fashion turns over, and how tightly the top names hold.
Year-to-year change in the top names (Jensen–Shannon divergence, measured on each register's leading 200 names so the two are compared on equal footing). Higher means a livelier, faster-moving fashion.
Share of all births taken by the ten most popular names. A century ago a handful of names ruled; both registers have spread out since — nearly in lockstep.
Sources: Office of the Registrar General, Ontario, Baby Names (1917–2024), via the Ontario Data Catalogue under the Open Government Licence – Ontario; and the U.S. Social Security Administration, National Data on baby names (1880–2024, windowed here to 1917–2024 to match Ontario). The two registers use different suppression floors — Ontario omits names given to fewer than five children a year, the U.S. likewise but on a far larger population — so churn is computed on each side's top 200 names by rank, within-set, which removes the distortion that a raw whole-distribution comparison would introduce. Part of the Make It Make Toonies register.