The COVID-19 pandemic has raised even greater concerns about a growing teacher shortage. In this study, administrative data on more than 140,000 Michigan traditional public and charter school teachers in an interrupted time series (ITS) framework is used to understand how teacher attrition and supply may have shifted after the onset of the COVID-19 pandemic. A brief review of the literature on teacher attrition and mobility trends during the pandemic is provided, followed by a description of the Michigan public school employee-level data and the methods of estimating mobility and attrition trends during the pandemic. The results suggest that Michigan teachers were "more" likely to leave the profession, "less" likely to leave their districts, and "more" likely to switch schools within their district after the 2020-2021 and 2021-2022 school years relative to pre-pandemic trends. Findings also show significant heterogeneity across teachers with different demographic characteristics and those working in different types of schools, districts, and communities. Overall, this knowledge will enable district administrators and lawmakers to craft policy that can better maintain equitable K-12 educational opportunities both in Michigan and nationally.