I got a concerned email from a client yesterday asking for help. AdWords was saying that it couldn’t target 60% of the Zip Codes one of her dealers had entered for a particular local campaign in Southern California. That sounded odd to me, as Google should be able to target the IP-dense So Cal region fairly well.
I entered one of the Zips she’d sent as not being targetable into Google Maps, which delivered me to the area in question and even added a nice dashed line around the Zip Code’s perimeter. The problem became apparent at once: this Zip Code covered a highway median, and nothing else.
Entering another handful of Zip Codes from her list, I found an empty field, a few more stretches of roadway, and one lonely post office. There are ~42k Zip Codes in the United States. Most of these represent groups of addresses, but many are delivery routes, PO boxes, or overseas military bases. If Google isn’t able to target a few of the Zips on your list, don’t panic, do some homework, and determine if you really want to target that parking lot after all.