Key PointsQuestionIs insurance status associated with interfacility transfer among patients with ST-segment elevation myocardial infarction (STEMI) presenting to the emergency department?FindingsIn this cohort study of 32 841 transferred patients with STEMI in California, uninsured patients had significantly lower odds of interfacility transfer compared with their insured counterparts regardless of the facility’s percutaneous coronary intervention capabilities.MeaningThese findings warrant further investigation to understand the characteristics of facilities and outcomes for uninsured patients with STEMI.