Should the voting age be lowered to 16?

San Francisco could soon become the first major American city to lower its voting age to 16. A local ballot measure under consideration this November would allow 16- and 17-year-old residents to participate in citywide elections. The voting age for state and federal elections would remain 18.

If the measure is passed, it would mark a major step in a growing movement to extend voting rights to younger Americans. In 2013 the Washington, D.C., suburb of Takoma Park, Md., became the first city in the country to lower its voting...