Years after its implementation, studies have shown a marked decline in youth tobacco use, particularly in the realm of electronic cigarettes. While it has not eliminated underage smoking entirely, Tobacco 21 successfully created a harder barrier of entry for youth, altering the trajectory of nicotine addiction for a new generation.

Public health advocates championed the law primarily to combat the surging popularity of vaping among middle and high school students.

A major point of contention was that 18-year-olds are considered adults who can vote, sign contracts, and join the military, yet are denied the right to buy tobacco.

Most underage smokers obtain tobacco from older peers. Raising the age to 21 cut off high schoolers' access to 18-year-old friends who could legally buy products.

Nicotine is highly addictive and can harm adolescent brain development, which continues until about age 25.

While the law passed with bipartisan support, it was not without heavy debate and criticism.