Drivers and disparities in air conditioning access across the United States

Air conditioning (AC) access is a critical adaptation to rising temperatures and extreme heat under climate change. Yet, fine-scale, national estimates of AC prevalence—and the social and geographic factors that shape access—remain scarce. Here, we use an original, nationally representative survey (n = 11,235) combined with high-resolution demographic, administrative, and remote sensing data to estimate AC access at state, core-based statistical area (CBSA), and county levels across the contiguous United States. Applying multilevel regression and post-stratification (MRP) with machine learning optimization, we map central AC, window units, and lack of AC, and validate estimates using four independent sources. We find sharp regional disparities: while 86% of counties report at least 90% access to some form of AC, prevalence remains low in higher-elevation western regions, particularly the Pacific Northwest and Rocky Mountains. Our analysis reveals that socioeconomic status, housing stock, and local climate are key predictors of AC access. These patterns expose an emerging adaptation gap, with implications for heat vulnerability, energy demand, and climate justice. By identifying where and why AC access is lacking, this work informs targeted interventions to reduce risk in a warming world.