BACKGROUND Prior to the introduction of JUUL, a high nicotine e-cigarette product that gained market predominance in 2017, adolescents who experimented with e-cigarettes mainly progressed to daily cigarette use. It is unknown how patterns of tobacco product use have changed since high nicotine e-cigarette products have gained market predominance. OBJECTIVE This longitudinal study examines temporal patterns of daily tobacco product use among ever users from the Truth Longitudinal Cohort (TLC). METHODS The analytic sample (N=5274) includes individuals aged 15-36 years, residing in the United States, who had ever used any tobacco product at Wave 7 (collected between February – May 2018) and provided information on tobacco use at Wave 9 (collected between November – December 2019). Respondents were asked to report on their use of e-cigarettes, cigarettes, and other combustible tobacco products (e.g., little cigars, cigarillos, cigars, hookah, smokeless tobacco, pipe tobacco) in the past 30 days. Use of any tobacco product on at least 25 days of the past 30 days was categorized as daily use. To determine temporal patterns of daily tobacco product use, variance estimates and 95% confidence intervals were calculated using STATA (Version 15.1). Survey weights were applied to obtain statistically valid estimates from longitudinal analyses. RESULTS During the 23-month observation period, there was an 1.9% increase in the prevalence of daily tobacco use, from 11.4% to 13.3%. Overall, daily cigarette use decreased from 6.7% (95% CI: 6.0 – 7.4) to 6.3% (95% CI: 5.7 – 7.0), while daily e-cigarette use increased from 3.3% (95% CI: 2.8 – 3.8) to 5.3% (95% CI: 4.8 – 6.0). A large proportion of daily tobacco product users used a single product exclusively. Among daily tobacco users, there was considerable stability of tobacco product use over time. Specifically, 63.9% (95% CI: 58.7 – 68.9) of daily cigarette smokers, 58.7% (95% CI: 51.0 – 66.2) of daily e-cigarette vapers, and 26.3% (95% CI: 9.2 – 51.2) of daily dual users stayed with their primary tobacco product. There was also some evidence of switching, as 7.4% (95% CI: 4.9 – 10.6) of daily cigarette smokers became daily e-cigarette vapers and 3.5% (95% CI: 1.3 – 7.4) of daily e-cigarette vapers became daily cigarette smokers. CONCLUSIONS Results demonstrate that although most daily tobacco users are likely to continue using their primary product over time, some daily users of combustible tobacco products will transition to daily e-cigarette use. Thus, policies and public education focused on reducing nicotine use are essential for implementing change in the trajectory of the nicotine addiction epidemic among youth and young adults.