Introduction: Firearms are the leading cause of death in US children and adolescents, but little is known about whether legal policies may be responsible. Methods: We conducted difference-in-differences analysis on CDC WONDER data before and after McDonald v. Chicago, the landmark 2010 Supreme Court decision on firearms regulation. States were divided into three groups, based on legal actions taken before and since 2010, most permissive, permissive, and restricted. Firearm mortality trends before (1999-2010) and after (2010-2023) were determined and compared across the three groups for all intents and by intent (homicide and suicide). Within the most permissive state grouping, pediatric firearm mortality by 2013 urbanicity and by observed race and ethnicity were conducted. For each US state, pre-and-post 2010 all-intent pediatric firearm mortality incident rates were compared. Results: There were 7130 excess pediatric firearms deaths in states with more permissive regulatory regimes than those with stricter frameworks, as well as higher rates of homicide and suicide. Non-Hispanic Black populations were disproportionately affected by these trends. Four states (California, Maryland, New York, and Rhode Island) had decreased pediatric firearm mortality after 2010, all of which were in the restrictive firearms law group. Conclusion: States with more permissive firearm laws have experienced greater pediatric firearm mortality during the post-McDonald v. Chicago era.

Dr. Krumholz reported receiving expenses and/or personal fees within the past 3 years from UnitedHealth, Element Science, Aetna, Reality Labs, Tesseract/4Catalyst, F-Prime, Siegfried and Jensen law firm, Arnold and Porter law firm, and Martin/Baughman law firm; being a co-founder of Refactor Health and HugoHealth; and being associated with contracts through Yale New Haven Hospital from the Centers for Medicare & Medicaid Services and through Yale University from Johnson & Johnson. No other disclosures were reported.

This study did not receive any funding.

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The study used only openly available public health data accessible through the CDC WONDER database.

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All data analyzed in this study are derived from the CDC WONDER database.