Purpose: Environmental hazards are unevenly distributed across communities and populations; however, little is known about the distribution of environmental carcinogenic pollutants and lung cancer risk across populations defined by race, sex, and rural-urban setting. Methods: We used the Toxics Release Inventory (TRI) database to conduct an ecological study at the county level (a total of 3,141 counties). Multiple linear regressions were used to assess the associations of carcinogenic discharges from TRI sites and lung cancer mortality rates at the county level in the United States during the years 1990 through 2007. Findings: We observed an excess risk of population lung cancer mortality associated with higher amounts of environmental carcinogen releases from TRI facilities in both males and females, and in both whites and African Americans. The strength of these associations tended to be stronger in African Americans. A significant dose-response relationship was observed for the total volume of carcinogen releases or carcinogen releases to the air, but not releases to water. These associations appeared to be present within nonmetropolitan counties but not metropolitan counties, and to be concentrated in certain urban-rural county typologies. Conclusions: Our results suggest that exposure to higher carcinogen releases from industrial or chemical facilities in rural areas may increase the risk of lung cancer mortality. Our findings add to the evidence for undertaking prudent efforts to limit the release of carcinogenic chemicals into the environment. (Contains 3 tables and 1 figure.)