A True P.I. Private Investigator

Houston's 378 advertising agency listings aren't clustered in one part of town. The 77007 zip code leads with 21 listings, followed by 77056 with 15 and 77002 with 14. Several other zips, including 77043, 77057, 77077, and 77092, each hold 13 listings, and 77008 rounds out the top group with 12. That spread means you can likely find an agency close to your own office rather than driving across the city for a meeting.

Every listing here comes with a phone number, and most, 364 out of 378, list a working website, so you can call two or three and compare quickly before committing to anyone. Paid placements are labeled Sponsored, and this category currently has none, so the order you're browsing is unaffected by any purchase. If you run one of these agencies and spot an old phone number or a broken site link, you can claim your listing and update the details yourself, which keeps your entry useful to anyone searching Houston for a firm to call.