Final answer:
Direct mail advertising is the strategy involving sending postcards or flyers to potential customers, useful particularly in areas with an older demographic.
Step-by-step explanation:
The form of advertising that involves sending postcards or flyers to potential customers is known as direct mail advertising. This traditional marketing strategy specifically targets a demographic identified by the campaign using physical mail. Although in the current digital age, the effectiveness of print media has diminished compared to online platforms, direct mail can still be significant, especially in areas where there's a demographic that appreciates tangible mail, such as districts with older voters. For a political campaign analyzing voter demographics, a blend of advertising media is crucial, using direct mail along with TV, radio ads, and online strategies tailored to the audience's preferences.