Is the US Chamber Guilty of Member-Inflating?

Mother Jones' Josh Harkinson has been looking into the US Chamber's claims to have 3 million members, one it has been invoking more frequently since it has come under increasing attack from companies that disagree with the Chamber's position. As Harkinson writes:

"The nation's largest business lobby may be much smaller than it appears. A review of archival press releases suggests that the US Chamber of Commerce-which will not disclose the names of its members-has vastly overstated its size in recent years, helping to make its controversial positions on health care and climate change look like a consensus of American businesses....

In February 1997, the Chamber's membership figure mysteriously jumped from 200,000 to 3 million, where it has remained ever since. The first use of the bigger number came less than two weeks before Chamber president Richard Lesher retired, soon to be succeeded by current president Tom Donohue. In congressional testimony and a press release, the Chamber suddenly described itself as representing "an underlying membership of more than three million businesses and organizations of every size, sector, and region." 

HuffPo has picked up an expanded on MoJo's questions.