From mass.gov:
The Massachusetts Presidential Primary will be held on Tuesday, February 5, 2008.
Wednesday, January 16, 2008 is the last date to register to vote and change party enrollment for this primary.
As the excitement builds, if you wish to participate, you'll need to be registered to vote in the city or town where you live. (If you've moved to a different community recently, you'll need to re-register).
You can register in person, by mail, or even at the Registry of Motor Vehicles when you renew your driver's license:
