Beginning in early 2020, public libraries in the United States faced unprecedented challenges presented by the outbreak of COVID-19, implementing several significant changes in response such as circulating physical materials outside the building, increasing access to library materials without requiring in-person visits, and expanding Wi-Fi access outside library buildings. This report builds on previous briefs, using state-level data to explore the nuanced landscape of public libraries and their responses to COVID-19. It presents the percentages of libraries that answered "Yes" to six COVID-19 questions included in the Public Libraries Survey (PLS) for FY 2020 and FY 2021. By examining how libraries adapted their services during the pandemic, deeper insights are gained into how they sustained access to materials, ensuring communities continued to receive vital information and resources. The analysis in this report focuses on the 9,021 public library systems in the 50 states and the District of Columbia that met the Federal State Cooperative System (FSCS) definition of a public library. This report presents findings both at the national and state levels, and the state profiles provide detailed findings for each state and by locales within the state. To supplement the quantitative analysis in this report, the American Institutes for Research (AIR) conducted semi-structured interviews with staff from eight state library administrative agencies (SLAAs) in winter 2024. AIR also analyzed open-ended text responses shared by three State Data Coordinators from their state-level surveys. Findings show that fewer public library systems reported buildings closed to the public due to COVID-19 policies in FY 2021 (57 percent) compared to FY 2020 (90 percent), and that electronic material circulation rates continued to increase through FY 2021, maintaining a trend first noted in FY 2018. The percentage of libraries allowing patrons to register for library cards online continued to increase in cities and suburbs, and libraries offering this option had higher electronic circulation per person than those that did not. Outside Wi-Fi access continued to be a popular way that public libraries met the digital needs of their communities, especially in rural and town libraries, and outside circulation of collection materials (e.g., curbside pick-up) remained a widely adopted service offered by libraries, with at least 80 percent offering it in both FY 2020 and FY 2021. Appendices include: (1) Detailed Tables; (2) State Report and Profile Methodology and Caveats; and (3) State and Territory Profiles. [The Public Libraries Survey is a collaborative effort between the Institute of Museum and Library Services and the SLAAs of all 50 states, the District of Columbia, and five outlying territories.]