What is a negative zip code?
Where your ads should appear is important—but where they shouldn't appear is just as crucial to your campaign's success. Location exclusion can allow you to prevent your ad from showing in certain areas, such as a city within a state, or a certain zip code that is not a part of your territory. This helps you use your budget wisely by preventing your ad from showing to people who most likely wouldn't have access to what you're offering.
When a zip code is listed as "negative", it instructs Google to exclude that area from the areas where your ads will be visible. This is most commonly done when there are two locations within the same city or town and each location owns a certain combination of zip codes for marketing.
For example, when two locations are in the same city, we list Location A’s contractual zip codes as negative zip codes in Location B’s campaign. We also list Location B’s contractual zip codes as negative zip codes in Location A’s campaign. This should prevent Location A’s ads from showing in Location B’s area and Location B’s ads from showing in Location A’s area.