There are more than 1,000 fossil fuel peaker plants operating across the U.S. today. Most of these peaker plants are sited in urban areas, usually in under-resourced communities. They run during times of high (“peak”) electricity demand, like hot days when air conditioners are blasting, polluting mainly low-income communities and communities of color. This fact sheet identifies the top ten metropolitan regions across the country where the health and well-being of its citizens are adversely impacted by an aging fleet of peaker plants. Based on a preliminary scan of publicly available data, these 10 regions are collectively burdened by nearly 200 peaker plants, representing a combined 48-gigawatt source of urban emissions. The fact sheet also highlights the findings of work being done in New York City to advance the replacement of peaker plants with battery storage and renewables.