US natural gas production increased by ∼43% between 2005 and 2015, but there is disagreement among existing studies on whether this growth led to increased methane emissions. We evaluate the likely contributions of atmospheric transport to an upward trend in atmospheric methane enhancements during 2007–2015, defined as the contribution of North American emissions to atmospheric observations across the US. We find that interannual variability (IAV) in transport yields an apparent upward trend in enhancements across much of the US during this time and can explain disagreements among existing studies over emissions trends. We further find that enhancements at satellite and in situ monitoring sites are 19% higher during El Niño than La Niña, possibly because air masses spend more time over North America on average during some years. The results show that accurate modeling of IAV in transport is a key prerequisite to quantifying emissions trends. Plain Language Summary US natural gas production increased from 18 to 27.1 trillion cubic feet per year between 2005 and 2015 as a result of the shale gas boom and the associated technological breakthrough of combining horizontal drilling and hydraulic fracturing. This increase in natural gas activity has caused concern about methane emissions, since methane is the primary constituent of natural gas and an important greenhouse gas. However, existing studies of US methane emissions trends have reached conflicting conclusions. Furthermore, atmospheric methane levels at many US observation locations have increased faster than the global mean, raising questions about whether increasing US natural gas production has led to increased emissions. In this study, we explore the roles of changing emissions versus meteorology in explaining recent increases in atmospheric methane enhancements across the US and we explore the meteorological factors that may be driving these trends. We find that variability in meteorology can explain this recent atmospheric increase. Overall, the results lend support for the conclusion that there was little upward trend in US methane emissions during this time. Key Points Atmospheric transport explains an upward trend in observed atmospheric methane enhancements across the US between years 2008 and 2015 The time modeled air masses spend over North America varies by 15%–20% among years and correlates with variability in methane enhancements Modeled methane enhancements at satellite and in situ monitoring sites are 19% higher during El Niño than La Niña