Background: Lung cancer is the leading cause of cancer-related mortality in the US and is projected to account for 127,070 deaths in 2023. While the lung cancer mortality rate has been decreasing over the last decade, demographic disparities in mortality still exist. We sought to determine the impact of demographic factors on lung cancer mortality and trends in the US. Methods: We queried the Centers for Disease Control database for mortality statistics with an underlying cause of death of lung and bronchus cancer (ICD-10 code C34.0.x) between the years 1999 – 2020. Age-adjusted mortality rates (AAMR) were calculated per 100,000 deaths. We assessed the AAMR by demographic variables, including race (Hispanic, Non-Hispanic White, Non-Hispanic Black, Non-Hispanic Asian or Pacific Islander, Non-Hispanic American Indian/Native American), geographic density (Urban, Suburban, Rural), sex, age (25-44, 45-64, 65+ years), and US Census Region. Temporal trends were evaluated using Joinpoint regression software. Average annual percent change (AAPC) was considered statistically significant if p < 0.05. Results: Between 1999 and 2020, lung cancer led to 3,380,830 deaths. The AAMR decreased by 42% from 55.1 to 31.8 with an associated AAPC of -2.6% (p < 0.001). In 1999, men had an AAMR of 76.8, almost twice as high as women, who had an AAMR of 40.2. These differences became less pronounced over time, and in 2020 men had an AAMR of 38.1, while women had an AAMR of 26.9. Between 1999 and 2020, rural populations experienced the highest AAMR at 52.3, and the slowest rate of decrease at -1.7% annually (p < 0.001), compared with urban populations who experienced the lowest AAMR of 40.6 and fastest AAPC decrease of -3.1% (p < 0.001). Non-Hispanic Black individuals experienced the highest AAMR at 49.8, with an annual decrease of -3.0% (p < 0.001), followed by Non-Hispanic White individuals who had an AAMR of 48.5 with an annual decrease of -2.5% (p < 0.001). Subgroup analysis demonstrated that Non-Hispanic Black men who resided in rural counties experienced the highest mortality at 60.2, with an associated decrease of -2.9% annually (p < 0.001). States in the 90^th percentile of mortality included Arkansas and Kentucky; states in the 10^th percentile of mortality included Hawaii and Utah. The West experienced the fastest decrease at -3.1% annually (p < 0.001), while the Midwest experienced the slowest decrease at -2.0% annually (p < 0.001). Conclusions: While lung cancer mortality has been decreasing since 1999, not all demographic groups have experienced the same rates of decline, and disparities in outcomes remain prevalent. Vulnerable subgroups may benefit from targeted interventions, such as tailored smoking cessation education and efforts to increase participation in clinical trials. Expansion of screening CT scans and telehealth platforms may also improve access to care for these populations.