This could be the start of a trend.
Maine is now the fourth state in two years to raise the legal smoking age from 18 to 21.
And lawmakers voted overwhelming to pass the measure, even overriding the governor's veto.
Supporters say the new age limit will reduce smoking-related deaths...because 95-percent of adults who smoke, start by age 21.
The law also tightens regulations on e-cigarettes and hookah pipes - which are popular with teenagers.
Critics say it will boost the black market for cigarettes.
And in his veto, the governor said it would hurt grocery and convenience stores.
California, Hawaii, and New Jersey have also raised the limits.
New Jersey's law goes into effect November 1st.