The combustion of municipal solid waste (MSW) to generate heat or electricity (waste-to-energy (WTE)) could reduce net greenhouse gas emissions in the United States compared with combusting methane from landfills. Moreover, negative CO2 emissions could be achieved with carbon capture and sequestration because 66% of the carbon in MSW is typically biogenic. For the 5-largest landfill sites in each state, we estimate that at least 58 and 11 have enough MSW to fuel WTE plants of >50 MWe and >100 MWe, respectively. Furthermore, half lie within 20 km of potential underground saline and other storage reservoirs. We estimate that the levelized electricity cost for WTE without CO2 capture is US$94/MWh and is US$285/MWh with amine-based post-combustion capture technology. The cost of CO2 capture is US$58/Mg CO2, resulting in a cost for carbon negative emissions of US$93/Mg CO2, substantially lower than for some geo-engineering methods, including capturing CO2 from air.