Print editions might be suffering declines, but newspapers broke an online record for traffic, according to a new report from NetRatings.

Online newspaper sites had 58 million unique visitors in September - an all-time record for any month - according to a Nielsen/NetRatings study conducted for the Newspaper Association of America, ClickZreports. Moreover, on average, some 56.9 million people visited newspaper sites each month in the third quarter, up nearly 24 percent from the year-ago period.

The NAA says social-media tools such as blogs, podcasts and video are responsible for the torrid pace of online newspaper readership growth. But a boost in online readership won't necessarily guarantee profits.

A Merrill Lynch report from earlier this week predicted industry profits could remain flat for years - and that it would take at least two decades for online newspaper ad revenues to comprise half of total newspaper revenues. Merrill also expects a slight drop in newspaper ad revenue in the fourth quarter.