Background: The number of cancer survivors in the United States is projected to exceed 20 million by 2024. Survivors are at risk of developing a second primary neoplasm (SPN) – a leading cause of survivor death. We described the risk of developing a SPN among survivors of common cancers (smoking-related vs non-smoking-related) in the United States. Methods: We identified patients aged ≥18 years who were diagnosed with a primary cancer from the 10 sites with highest survival rates and stratified as smoking-related (urinary bladder, kidney & renal pelvis, uterine cervix, oral cavity & pharynx, and colon & rectum) and non-smoking related (prostate, thyroid, breast, corpus & uterus, and non-Hodgkin lymphoma) from Surveillance, Epidemiology, and End Results (2000-2015). SPN was defined as the first subsequent primary cancer occurring ≥2 months after first cancer diagnosis. Excess SPN risk was quantified using standardized incidence ratios (SIRs) stratified by sex. Results: A cohort of 2,908,349 patients (50.1% female) was identified and 260,267 (9.0%) developed SPN (7.6% of females and 10.3% of males). All index cancer sites were associated with a significant increase in SPN risk for females and males (except prostate cancer). Index smoking-related cancers (SIR range 1.20 – 2.17 for females and 1.12 – 1.91 for males) had higher increased risk of SPN than non-smoking-related cancers (SIR range 1.08 – 1.39 for females and 0.55 – 1.38 for males) relative to the general population. Conclusions: Nearly 10% of cancer survivors developed an SPN, and those with smoking-related cancers had higher risk. Given the increasing number of cancer survivors and importance of SPN as a cause of cancer death, these findings can improve secondary prevention and surveillance guidelines.