Despite the decline in the rate of coronary heart disease (CHD) mortality, it is unknown how the 3 strong and modifiable risk factors - alcohol, smoking, and obesity -have impacted these trends. We examine changes in CHD mortality rates in the United States and estimate the preventable fraction of CHD deaths by eliminating CHD risk factors. We performed a sequential time-series analysis to examine mortality trends among females and males aged 25 to 84 years in the United States, 1990-2019, with CHD recorded as the underlying cause of death. We also examined mortality rates from chronic ischemic heart disease (IHD), acute myocardial infarction (AMI), and atherosclerotic heart disease (AHD). All underlying causes of CHD deaths were classified based on the International Classification of Disease 9th and 10th revisions. We estimated the preventable fraction of CHD deaths attributable to alcohol, smoking, and high body-mass index (BMI) through the Global Burden of Disease. Among females (3,452,043 CHD deaths; mean [standard deviation, SD] age 49.3 [15.7] years), the age-standardized CHD mortality rate declined from 210.5 in 1990 to 66.8 per 100,000 in 2019 (annual change -4.04%, 95% CI -4.05, -4.03; incidence rate ratio [IRR] 0.32, 95% CI, 0.41, 0.43). Among males (5,572,629 CHD deaths; mean [SD] age 47.9 [15.1] years), the age-standardized CHD mortality rate declined from 442.4 to 156.7 per 100,000 (annual change -3.74%, 95% CI, -3.75, -3.74; IRR 0.36, 95% CI, 0.35, 0.37). A slowing of the decline in CHD mortality rates among younger cohorts was evident. Correction for unmeasured confounders through a quantitative bias analysis slightly attenuated the decline. Half of all CHD deaths could have been prevented with the elimination of smoking, alcohol, and obesity, including 1,726,022 female and 2,897,767 male CHD deaths between 1990 and 2019. The decline in CHD mortality is slowing among younger cohorts. The complex dynamics of risk factors appear to shape mortality rates, underscoring the importance of targeted strategies to reduce modifiable risk factors that contribute to CHD mortality.