IMPORTANCE: Menopausal hormone therapy (MHT) is the treatment of choice for symptoms of menopause. However, its adoption is hindered by the risk-benefit trade-off in relation to acute and chronic diseases. OBJECTIVE: To evaluate trends in and correlates of MHT use among postmenopausal women in the US from 1999 to March 2020. DESIGN, SETTING, AND PARTICIPANTS: This serial cross-sectional analysis of MHT use used data from the nationally representative National Health and Nutrition Examination Survey (NHANES). Participants included noninstitutionalized US postmenopausal women from 10 NHANES study cycles (1999-2000 to 2017-March 2020 [pre-COVID-19 pandemic]). Data were analyzed from December 2023 to April 2024. EXPOSURES: NHANES study cycle. MAIN OUTCOMES AND MEASURES: Prevalence of MHT use was extracted from the prescription medication data collected during NHANES household interviews. MHT formulations were determined by hormone type. RESULTS: Data on 13 048 US postmenopausal women (47.1% ≥65 years old) were analyzed. From 1999 to 2020, the prevalence of MHT use decreased among women of all age groups, from 26.9% (95% CI, 22.6%-31.7%) in 1999 to 4.7% (95% CI, 3.4%-6.5%) in 2020. Until 2002, MHT use was highest among women aged 52 to 65 years, but since 2005, MHT use has been highest among women younger than 52 years. MHT use decreased by 23.5% (95% CI, 11.4%-35.6%), 31.4% (95% CI, 23.4%-39.5%), and 10.6% (95% CI, 6.3%-14.8%) for women younger than 52 years, 52 years to younger than 65 years, and 65 years and older, respectively. Prevalence of MHT use decreased from 13.8% (95% CI, 8.5%-21.7%) to 2.6% (95% CI, 1.5%-4.6%) for Hispanic women, 11.9% (95% CI, 8.5%-16.3%) to 0.5% (95% CI, 0.2%-1.1%) for non-Hispanic Black women, and 31.4% (95% CI, 27.1%-36.1%) to 5.8% (95% CI, 4.1%-8.2%) for non-Hispanic White women. Non-Hispanic White women consistently had the highest prevalence of MHT use. Estrogen-only formulation accounted for more than 50% of the MHT for most study periods. The prevalence of MHT use varied by family income-to-poverty ratio, health insurance coverage in all racial and ethnic groups, weight, and smoking status among non-Hispanic White women, as well as by education attainment among non-Hispanic Black and Hispanic women. CONCLUSIONS AND RELEVANCE: Results of this cross-sectional study show that over the past 2 decades, MHT use declined among US postmenopausal women of all age and racial and ethnic groups. Women of racial and ethnic minority groups had lower prevalence of MHT use compared to non-Hispanic White women.