According to a Huffington Post editor who asked not to be named, HuffingtonPost.com passed NYTimes.com in traffic last month. The May numbers reflect a boost seen by a number of news sites. (With 10 million unique visitors, The Atlantic's digital properties, including The Atlantic Wire, also broke an all time record.) But passing The Times is a different kind of milestone for the battle between Arianna Huffington's five year site and the Gray Lady. While our source could not confirm the numbers, a report from Twitter claims that HuffPost bested The Times with 35.5 million unique visitors to The Times's 33.59 million unique visitors on comScore. While other traffic sites reported HuffPost passing The Times earlier this year, comScore is the advertising industry standard.

The leapfrogging should not come as a surprise to The Times. Upon instituting a their new paywall on March 28, executive editor Bill Keller said he expected traffic to take a hit in the short run. Meanwhile, the paper claimed that the revenue brought in by the pay wall would justify the difference in traffic numbers when it came down to the bottom line. The race to beat The Times took another turn in April when the Daily Mail passed The Huffington Post in traffic, leading many to realize that it wasn't just a head-to-head between the American sites. However, HuffPo's time on top may be affected by Jill Abramson's ascent to the executive editor seat in September. The well-publicized spat between Keller and Huffington over the ethics of aggregation made some wonder if The Times was still sticking to a head-in-the-sand approach to new media.

Really, nobody should be surprised by the latest news, though. As the chart below reflects, Henry Blodget predicted the event weeks ago:

UPDATE (5:43 PM EST): A closer look at the new traffic numbers show that the Huffington Post numbers may be misleading as the stats are somewhat convoluted in the wake of the AOL-HuffPost merger. Kristin Mason at The New York Times told us in an email:

It’s an important point for readers to understand that HuffingtonPost’s May traffic is now reflecting AOL News traffic, as the AOLNews.com domain is redirecting to HuffingtonPost.com.  (AOL News dropped from 12.4 million unique in April to 1.9 million in May, so that should give some perspective about the redirect.) 

Jeff Bercovici at Forbes offers a more in depth look at how HuffPost's traffic stats are misleading, citing Experian Hitwise for the skyrocketing number of redirects coming from AOLNews.com. We've reached out to The Huffington Post for details on the apparent traffic padding and will update this post when we hear back.

(Full disclosure: I worked as an editor at The Huffington Post from June 2008 through November 2009)