AbstractEighty percent of US oil and natural gas (O&G) production sites are low production well sites, with average site-level production ≤15 barrels of oil equivalent per day and producing only 6% of the nation’s O&G output in 2019. Here, we integrate national site-level O&G production data and previously reported site-level CH₄ measurement data (n = 240) and find that low production well sites are a disproportionately large source of US O&G well site CH₄ emissions, emitting more than 4 (95% confidence interval: 3—6) teragrams, 50% more than the total CH₄ emissions from the Permian Basin, one of the world’s largest O&G producing regions. We estimate low production well sites represent roughly half (37—75%) of all O&G well site CH₄ emissions, and a production-normalized CH₄ loss rate of more than 10%—a factor of 6—12 times higher than the mean CH₄ loss rate of 1.5% for all O&G well sites in the US. Our work suggests that achieving significant reductions in O&G CH₄ emissions will require mitigation of emissions from low production well sites.