Well, 16+ voting isn't novel - lowering the age has been
   happening a lot recently in various parts of the world. I'm not
   trying to convince you - and I didn't even KNOW it was "a thing"
   'til last night. But it's interesting
   [1]http://www.fairvote.org/reforms/right-to-vote-amendment/lowering-the-voting-age/
   Also, Washington D.C. just means that: City of Washington D.C
   but larger areas in different parts of the world have already
   switched. It allows them to discuss the issues while they're
   still in school too - something to consider.* When they're out
   of school, out of reach of mandated adult influence... they're
   on their own, alone, and easily manipulated with nobody to say,
   "Um... no."

References

   Visible links
   1. http://www.fairvote.org/reforms/right-to-vote-amendment/lowering-the-voting-age/