According to this eMarketer article, “Nearly two-thirds of small businesses surveyed by Western Wats in an AT&T-commissioned study said they advertised in a printed yellow pages directory.“

I might be wrong as I’m not as familiar with the US market, but that number seems high based on my Canadian directory business experience. Up here, Yellow Pages Group has 395,000 customers (2006 annual report) which gives them, depending on who you talk to, between 20% and 40% penetration of the Canadian SME market. The US market is much more competitive though (some cities have 5+ competitive printed directories) and that might be why more SMEs are claiming they advertise in printed business directories.