Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death in the United States. Most deaths from lung cancer are caused by cigarette smoking and exposure to secondhand smoke. Large variations in lung cancer, smoking behavior, and tobacco control programs and policies have been observed among states. Effective tobacco control policies can decrease smoking prevalence, ultimately leading to decreases in lung cancer. To assess lung cancer incidence by state, CDC analyzed data from the National Program of Cancer Registries (NPCR) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program for the period 1999-2008. To assess smoking behavior by state, data from the Behavioral Risk Factor Surveillance System (BRFSS) for the period 1994-2009 were analyzed. This report summarizes the results of these analyses. From 1999 to 2008, decreases in lung cancer incidence were observed among men in 35 states and among women in six states. Regionally, the lowest rates and most rapid rate of decline in lung cancer were concentrated among states in the West, correlating with low smoking prevalence and high ratios of former smokers to ever smokers. Further reductions in smoking prevalence are critical to continue the decline in lung cancer incidence.