Almost all climate change regulations in the US have stipulations to reduce carbon dioxide and methane emissions by economic sector, so being able to accurately monitor and assess these emissions is crucial to being able to assess compliance with these regulations. Emissions estimates at the national level have been shown to be fairly accurate, but at the state level there is still much uncertainty. As part of the Paris Agreement, the US pledged to "decrease its GHG emissions by 26–28 % relative to 2005 levels by 2025 as part of the Paris Agreement negotiated at COP21. To comply with these regulations, it is necessary to quantify emissions from specific source sectors. A source sector is a sector of the economy that emits a particular greenhouse gas, i.e. methane emissions from the oil and gas industry, which the US has pledged to decrease by 40–45 % relative to 2012 levels by 2025 as a more specific action towards achieving its Paris Agreement contribution.