U.S. ad agency employment is at its highest level since 2001, a sign of strength in an industry that is adapting to the digital era.

Advertising agencies employed 199,100 people in October, the highest level since May 2001, according to Ad Age Datacenter's analysis of jobs data released today by the Bureau of Labor Statistics.

Robust employment is an indication of how the agency business is successfully navigating marketing's transition to digital. Agencies from all advertising and marketing-services disciplines generated nearly 40% of 2014 U.S. revenue from digital services, according to Ad Age Datacenter's analysis.

Ad agencies have added 38,500 jobs since agency employment hit its recession-era nadir of 160,600 in January 2010.

Employment remains below its all-time peak of 207,400 in August 2000 in the frenzy of the dot-com bubble.

Agency employment in 2000 and 2001 was artificially boosted by ad spending -- largely offline, in TV and print -- by short-lived dot-coms flush with cash from venture capital and initial public offerings.

The dubious dot-coms are long gone, but agencies are more digital than ever.

Chart by Chen Wu.