EPA announced the Mercury and Air Toxics Standard (MATS) in December 2011, which established performance standards to reduce emissions of mercury, acid gases, and non-mercury metallic toxic pollutants from coal- and oil-fired power plants. Between 2010 and 2017, emissions of mercury from power plants dropped 86 percent. A combination of factors contributed to this decline, such as the shutdown and reduced utilization of coal-fired power plants, the conversion of coal-fired power plants to natural gas, and the installation of pollution control technology to reduce mercury. Control technologies include selective catalytic reductions (SCR) with flue-gas desulfurization (FGD), activated carbon injection (ACI), ACI with fabric filter (FF), or electrostatic precipitators (ESP). In 2010, coal-fired electric generating units (EGUs) with post-combustion control devices accounted for half of all electricity generation; in 2017, that share increased to over 90 percent. This analysis will delve into mercury emissions monitoring from power plants as well as the trends that led to the significant decrease in mercury emissions from the power sector over the last decade. Data from all MATS-affected emission sources are available at ftp://newftp.epa.gov/DMDnLoad/emissions/mats/.