Long COVID is a condition encompassing a wide range of health problems that emerge, persist, or return following COVID-19. CDC analyzed national repeat cross-sectional Household Pulse Survey data to estimate the prevalence of long COVID and significant related activity limitation among U.S. adults aged ≥18 years by age group. Data from surveys completed between June 1-13, 2022, and June 7-19, 2023, indicated that long COVID prevalence decreased from 7.5% (95% CI = 7.1-7.9) to 6.0% (95% CI = 5.7-6.3) among the overall U.S. adult population, irrespective of history of previous COVID-19, and from 18.9% (95% CI = 17.9-19.8) to 11.0% (95% CI = 10.4-11.6) among U.S. adults reporting previous COVID-19. Among both groups, prevalence decreased from June 1-13, 2022, through January 4-16, 2023, before stabilizing. When stratified by age, only adults aged <60 years experienced significant rates of decline (p<0.01). Among adults reporting previous COVID-19, prevalence decreased among those aged 30-79 years through fall or winter and then stabilized. During June 7-19, 2023, 26.4% (95% CI = 24.0-28.9) of adults with long COVID reported significant activity limitation, the prevalence of which did not change over time. These findings help guide the ongoing COVID-19 prevention efforts and planning for long COVID symptom management and future health care service needs.