Established in 1933, the Traffic Audit Bureau for Media Measurement Inc. is a non-profit organization whose historical mission has been to audit the circulation of out of home media in the United States. Recently TAB's role has been expanded to lead and/or support other major out of home industry research initiatives.

Governed by a tripartite board comprised of advertisers, agencies and media companies, the TAB acts an independent auditor for traffic circulation in accordance to guidelines established by its Board of Directors. These rules govern both how audits are conducted as well as how circulation figures are reported.