The report gives results of a field study of 21 U.S. landfills with gas recovery systems, to gather information that can be used to develop an empirical model of methane (CH4) emissions. ite-specific information includes average CH4 recovery rate, landfill size, tons of refuse (refuse mass), average age of the refuse, and climate. orrelation analysis showed that refuse mass was positively linearly correlated with landfill depth, volume, area, and well depth. egression of the CH4 recovery rate on depth, refuse mass, and volume was significant, but depth was the best predictive variable (R2 = 0.53). efuse mass was nearly as good (R2 = 0.50). one of the climate variables (precipitation, average temperature, dewpoint) were correlated with the CH4 recovery rate or with CH4 recovery per metric ton of refuse. uch of the variability in CH4 recovery remains unexplained, and is likely due to between-site differences in landfill construction, operation, and refuse composition. odel for global landfill emissions estimation is proposed.