Abstract Background Accurate estimates of the population sizes of men who have sex with men (MSM) are essential for evaluating HIV-related interventions. We aimed to estimate MSM populations at county and state levels using recent data from the decennial census and the National Health and Nutrition Examination Survey. Methods We used 2020 Decennial Census data to calculate a weight for each U.S. county, reflecting the proportion of male-male partner households relative to counties of similar urbanicity based on the 2013 National Center for Health Statistics Urban–Rural Classification Scheme. We applied these weights to urbanicity-stratified estimates of the prevalence of adult men who reported sex with a man in the past 12 months, derived from National Health and Nutrition Examination Survey (2015–2020). Multiplying these percentages by adult male populations produced county estimates, which were aggregated to state levels. Results We estimated approximately 2.1 million MSM in the United States, representing 1.7% of adult males. State-level estimates ranged from 0.3% in Wyoming (n = 675) to 3.7% in the District of Columbia (n = 9709). California had the largest MSM population (n = 318 612; 2.1%), followed by Florida (n = 191 199; 2.3%) and Texas (n = 173 751; 1.6%). At the county level, Los Angeles County, CA, had the largest MSM population (n = 82 513; 2.1%), followed by Cook County, IL (n = 39 580; 2.0%), and Broward County, FL (n = 34 321; 4.7%). Broward County, FL (4.7%), and San Francisco County, CA (4.6%), had the highest proportions relative to their male populations. Conclusions County- and state-level MSM estimates provide crucial denominators for calculating disease rates and informing public health interventions.
Islek et al. (Thu,) studied this question.