Although most persons over 5 years of age drown in open water, few laws have sought to regulate open water swim sites. We examined the association between regulations for designated open water swim sites and open water drowning death rates by state.Using International Classification of Disease (ICD)-10 codes in the CDC Web-based Injury Statistics Query and Reporting System (WISQARS), we identified and calculated open water drowning deaths involving all ages from 2012 to 2017 for 50 states and calculated open water drowning death rates. We then identified and categorised types of state regulations (lifeguards, water quality, rescue equipment, tracking/planning/reporting and signage) for open water swim sites in place in 2017 for a sample of 30 states (20 high-drowning, 10 low-drowning). Analyses evaluated associations between open water drowning rates in three groups (overall, youth and non-white) and the total number and types of state regulations.Swim site regulations and open water drowning death rates for 10 839 victims were associated in all regression models. States with more types of regulations had lower open water drowning death rates in a dose-response relationship. States lacking regulations compared with states with all five types of regulations had open water drowning death rates 3.02 times higher among youth (95% CI 1.82 to 4.99) and 4.16 times higher among non-white residents (95% CI 2.46 to 7.05). Lifeguard and tracking/planning/reporting regulations were associated with a 33% and 45% reduction in open water drowning rates overall and among those aged 0-17 years.States' open water swim area regulations, especially addressing tracking/planning/reporting and lifeguards, were associated with lower open water drowning death rates.