Strained hospital capacity is associated with adverse patient outcomes. Anecdotal evidence suggests that during the COVID-19 pandemic in the US, some hospitals experienced capacity constraints while others in the same market had surplus capacity, a phenomenon known as "load imbalance." Our study evaluated the prevalence of intensive care unit load imbalance and the characteristics of hospitals most likely to be over capacity while other nearby hospitals were under capacity. Of the 290 hospital referral regions (HRRs) analyzed, 154 (53.1 percent) experienced load imbalance during the study period. HRRs experiencing the most imbalance had higher proportions of Black residents. Hospitals with the highest Medicaid patient shares and Black Medicare patient shares were significantly more likely to be over capacity, while other hospitals in their market were under capacity. Our findings highlight that hospital load imbalance was common during the COVID-19 pandemic. Policies to coordinate transfers may decrease strain during periods of high demand and ease the burden on hospitals that serve a higher proportion of patients from racial minority groups.