Importance: Updated data on the patterns of e-cigarette use among adults in the US are needed.

Question: What are the recent patterns in current and daily e-cigarette use among US adults?

Findings: In this cross-sectional study involving 994 307 adults from US states and territories that reported data on e-cigarette use in the 2017, 2018, and 2020 Behavioral Risk Factor Surveillance System, the prevalence of current e-cigarette use increased from 4.4% to 5.5% between 2017 and 2018 but decreased slightly to 5.1% in 2020; this decrease, though modest, was observed mainly among those aged 18 to 20 years. The prevalence of daily e-cigarette use increased consistently, from 1.5% in 2017 to 2.1% in 2018 and 2.3% in 2020, with the most significant increase among adults aged 21 to 24 years.

Meaning: This study found a slight reduction in current e-cigarette use but consistent increases in daily e-cigarette use, suggesting greater nicotine dependence that warrants continued surveillance.