The Interactive Advertising Bureau released new figures Monday showing that advertising supported Internet companies contributed $530 billion to the economy in 2011 and are, in some way, responsible for 5.2 million U.S. jobs.

The IAB-commissioned report from Harvard Business School, which updated a similar 2009 report, found Internet-based companies in every congressional district in the United States. About 2 million people are directly employed by Internet ad-supported firms, the report said.

An additional 3.1 million jobs, including those in Internet advertising and digital advertising analysis, would not exist without the sector.

Many of those companies are one-person businesses, including developers selling apps or entrepreneurs selling goods through services such as Amazon, eBay or the e-commerce Web site Etsy.

Although consumer-facing companies such as Facebook, YouTube and Twitter are the most visible part of the sector, the report found that jobs grew fastest in the digital advertising sector: ad networks, ad exchanges and ad analytics firms. Infrastructure jobs saw the largest increase (300 percent) between 2009 and 2011, followed by jobs in the consumer support services area.

The growth of the ad-supported Internet is a particularly encouraging given the U.S. economic climate, IAB chief executive Randall Rothenberg said in a statement.

“The rapid growth of the ad-supported Internet has become a major driver in the U.S. economy,” Rothenberg said. “With encouragement from regulators and legislators in Washington, D.C. and other world capitals, there is no doubt that the interactive marketplace will bring an even greater number of jobs into the fold — not only in America, but across the globe — providing strong economic value in the years to come.