ComScore said HuffingtonPost.com received 35.6 million unique visitors in May, up from 29.9 million the previous month, while NYTimes.com received 33.6 million unique visitors in May, up from 32.9 million the previous month.
The Huffington Post's traffic has surged over the past year, according to comScore, while that of NYTimes.com has remained relatively steady. The New York Times began charging readers for full access its website in late March.
In May 2010, HuffingtonPost.com received 23.8 million visitors, comScore said, while NYTimes.com welcomed 32.5 million.
The Huffington Post was launched by Greek American author and columnist Arianna Huffington in May 2006 and sold to Internet company AOL in February for $315 million.
The Huffington Post surged past 30 million visitors for the first time in March, apparently receiving a boost from the tie-up with AOL.
Yahoo! News remained the top US news site in May with 90.3 million unique visitors, comScore said, followed by CNN with 82.3 million.