negative zip code is a zip code Google is instructed to exclude from a campaign.
This means that we add zip codes to your campaign that we do not want your ads
to show in. This is most commonly done when there are two locations within the
same city or town.
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.