Door hanger left by an election canvasser campaigning for Republican John McCain in 2012.
Going door to door to canvass undecided, indifferent, and lazy voters is a time-honored tradition. To be effective, canvassing requires feet on the ground, a business-like organization of campaign staff and volunteers. Canvassing has persisted well into the television and Internet age, guided by predictive models to determine how to turn out the vote and win elections.