Marketing agencies in St. Louis: 290 offices on both sides of the river and how to check an agency's references

For St. Louis-area businesses choosing an agency, and for vendors selling to agencies in Missouri and Metro East Illinois. Figures cover the 15-county metro, including the independent city of St. Louis.

The St. Louis agency market

US Census Bureau, County Business Patterns 2023, St. Louis, MO-IL Metro Area (CBSA 41180), NAICS 5418 (advertising, public relations and related services):

So 255 offices have fewer than 20 people, 24 have 20 to 99 and 11 have 100 or more.

City, county and the Illinois side

Employees per office is our calculation. The city is the headquarters market: fewer offices, but large ones. The county is where most independents work. The two Illinois counties together have 19 small offices. "Not reported" is the Census Bureau's flag for a published figure that confidentiality noise moved by 5% or more.

Limits. CBP counts establishments with paid employees in March 2023, so a firm with a downtown office and a Clayton office counts twice, and freelancers aren't counted. Codes are NAICS 2017.

What kind of firm, by code

The rows add up to 290. The bigger story is outside 5418: 342 marketing consulting offices (541613) employ 8,288 people, about 24 per office, which is unusual: in the San Diego, Philadelphia, Dallas and Minneapolis areas, for example, consultancy offices average 4 to 12 people (same Census file). Firms that sell marketing strategy, planning and sales management advice are coded there, so search both codes. The metro also has 127 design studios (541430), and the Census index files custom SEO and web page design under 541511, custom computer programming.

Checking an agency's references

Agencies offer their happiest clients. A reference you find yourself tells you more.

1. Pick your own. Choose a client from the agency's case studies or client list, not only the two it suggests.
2. Find one that left. Ask the agency which clients it lost in the last two years and why; call one.
3. Use public records where they exist. Federal contracts are published with the buyer, scope, value and dates. For example, Mediacross (2001 South Hanley Road, St. Louis County) holds a Navy contract for advertising and recruiting services with $16,015,927.73 obligated for January 2024 to December 2026, on USAspending. A record like that confirms scale and staying power, and tells you which contracting office to ask about performance.
4. Confirm the entity on the Missouri Secretary of State's business entity search; an Illinois firm registers with Illinois.
5. Ask the questions below and take notes.

1. What did you hire them to do, and did the scope change?
2. Who from the agency worked on your account day to day? Are they still there?
3. Did they hit the results you agreed at the start? How did they report them?
4. Were invoices what you expected? Any surprise fees or markups?
5. When something went wrong, how fast did they tell you, and what did they do?
6. Did you keep your ad accounts, analytics and files in your own name?
7. If you left, how was the handover?
8. Would you hire them again for the same job?

Questions 4 and 6 have rules behind them. Google requires agencies to disclose any separate management fee in writing before the first purchase and on every invoice, and to give advertisers their Google Ads customer ID on request. Omnicom's 2025 10-K lists the main ways agencies charge (hourly or agreed fees, commissions on media, incentives tied to results and pass-through costs), so a reference should be able to tell you which applied.

Contract points to settle

• Creative rights. Ask for a signed copyright assignment. The US Copyright Office explains that commissioned work is a work made for hire only in nine narrow categories with a signed agreement.
• Data. Analytics Administrator access stays with you; customer lists come back at the end.
• Team. Name the account lead, with a right to approve a replacement.
• Cost. Ask for the plan as roles, hours and rates. Local agency offices paid an average of $81,422 per employee in 2023, about 87% of the US industry average.

The holding companies' 10-Ks won't help you place their local offices: Omnicom's names only its principal corporate offices and Stagwell's lists office countries, not cities. Nor does EDGAR show any listed company in SIC 7310 to 7319 with a St. Louis-area business address.

Selling to St. Louis agencies

Two territories need two approaches. The city's 60 offices are large, so expect department heads, operations and finance in the deal. The county's 157 offices are mostly owner-run. Don't leave out the consultancies: 342 offices with 8,288 people buy the same research, data, software and freelance services as agencies, and the larger ones buy at scale.

Illustrative example. The vendor, price and conversion rate are invented.

Gateway Bench (gatewaybench.example) places freelance copywriters, designers and media planners with agencies, earning a 20% margin on about $6,000 a month per placement, or $1,200. Its first list is the 11 offices with 100 or more employees and the 24 with 20 to 99, plus the larger consultancies. If an illustrative 15% of 35 agency offices use it for one placement a quarter, that's five offices, 20 placements and $24,000 a year in margin. The opener is a hiring signal: an agency posting for a contract role is already looking. Bebop finds the agencies that are hiring and the person who staffs projects.

Subject: The [role] opening

Hi [first name],

I saw [agency] is looking for a contract [role]. When a project lands before the hire does, the gap usually falls on your existing team.

We have [number] vetted [role]s in St. Louis available within [days], on [terms, e.g. weekly billing with no placement fee].

Want two profiles for the [client or project type] work?

[Your name]
[Company, postal address]
Reply "no" and I won't follow up.

St. Louis sources

Next step: compare St. Louis with the national groups in the largest advertising agencies and how to build a list, or see the largest companies in St. Louis for the region's biggest potential clients.