Introduction: Pediatric critical care providers in Wisconsin perceived a stark decline in the volume of PICU admissions in the spring of 2020, coinciding with the advent of COVID-19. Wisconsin presents a unique opportunity to study the effects of COVID-19 on pediatric critical care because its five collaborative PICUs serve the state's entire population of critically ill children. We designed this study to determine (1) if the 2020 springtime decline in PICU admissions was different than the usual seasonal decline and (2) if certain types of PICU admissions were responsible for this decline. Methods: Using the Virtual Pediatric Systems (VPS, LLC) registry, investigators from the five PICUs in the State pooled data from all 25,390 PICU admissions between 3/25/2015 and 5/13/2020. Approximated admission dates, all associated diagnoses, and diagnostic categories (e.g., respiratory) were recorded. Admissions were characterized as scheduled or unscheduled and trauma or non-trauma. The admissions during the study period, 3/25/2020 - 5/13/2020 (when Wisconsin's Safer at Home Orders were in force), were compared to admissions in seasonally-matched control periods during the previous five years. Results: The total weekly PICU admission rate fell from 94 ± 10 during the control period to 57 ± 11 during the study period, 41% lower than expected (p< 0.001) corrected for admission growth between 2015 and 2020. Respiratory viral admissions fell from 13 ± 5 to 4 ± 4 (72% lower than expected, p< 0.001), scheduled admissions fell from 28 ± 6 to 13 ± 7 (53% lower than expected, p< 0.001), and trauma admissions fell from 5 ± 2 to 4 ± 2 admissions per wk (32% lower than expected, p = 0.049). The categories of respiratory viral admissions, scheduled admissions, and trauma admissions contained distinct groups of critically ill children and accounted for 68% of the total decline in admissions. Conclusions: This collaborative effort of the Wisconsin Pediatric Critical Care Consortium describes how statewide PICU admission patterns changed during the beginning of COVID-19. Throughout Wisconsin's Safer at Home Orders, PICU admissions were 41% lower than expected compared to seasonal trends observed in the previous five years. A decline in respiratory viral, scheduled, and trauma admissions accounted for the majority of the total PICU admission decline.