Regional differences in ASD inpatient care remain understudied. We used the Nationwide Inpatient Sample to examine contributory causes and potential determinants associated with regional variations in ASD hospitalizations. We performed univariate and multivariate analyses to identify differences in ASD hospitalizations across four U.S. Census Bureau-defined regions. Our results revealed considerable variations in ASD hospitalizations across U.S. regions. Compared with patients in the Northeast, those in the Midwest, South, and West were less likely to be hospitalized for ASD. Significant differences were observed among regions with regard to the effect of health insurance type, hospital length of stay, hospital bed size, hospital location and teaching status on ASD hospitalizations. The region-specific analysis provides direction for further investigation.