Who should not buy billboards?

Anyone needing attributable conversions this quarter, niche-audience products without geographic clustering, and budgets too small to reach measurable frequency in their chosen market. Run the spend through a planner before committing.

Is billboard advertising effective?

Q: Is billboard advertising effective?

For brand outcomes (awareness, recall, branded search lift) the evidence is solid and the market's 19 consecutive growth quarters to a record $9.46B (OAAA 2025) show sustained buyer conviction. For tracked direct response it is weak: attribution is modeled, not click-level. Effectiveness depends on frequency, simple creative and flight length.

The short answer

The strongest neutral evidence is revenue behavior: US OOH has grown 19 consecutive quarters to a record $9.46B, with digital up 10.5% OAAA FY2025; sophisticated buyers keep returning. Study-level evidence supports brand outcomes: awareness, recall, branded search. Direct-response attribution is the thin end, and any claim otherwise should name its methodology.

Where the evidence is strong

Recall and attention: OAAA-commissioned consumer studies consistently find OOH among the most-noticed formats; the studies live on OAAA's research pages OAAA FY2025 and are seller-side-funded, which you should say in the deck footnote.
Brand lift under frequency: exposed-vs-control surveys show awareness movement when flights sustain frequency over weeks, not days.
Search lift by geography: flight-DMA vs control-DMA branded search comparisons are reproducible in your own analytics, no vendor required; that design is built into the $25k test.

Where it is thin, said plainly

Footfall attribution: panel-based, vendor-run, directional at best (measurement limits).
Last-click anything: DOOH will not appear in your attribution tool; its effect surfaces as lifted baselines on other channels (the support-channel framing).

The conditions that drive measured wins

Frequency over reach: one board seen daily for a month beats five boards seen once. Creative simplicity: a highway glance is seconds; seven words and a mark outperform paragraphs (specs). Flight length: brand metrics move over 4-12 weeks, so judge at the flight level, priced honestly against the published bands on the rate board. Full stat context: statistics; quick answers: FAQ.