The ComScore list of the top 50 most visited websites shows search engines, news sites and social media attract the most visitors using desktop computers for their browsing, CNET reported Monday.
More than 224 million unique users make up the desktop Internet-using population, said ComScore, which did not include mobile traffic in the list.
Yahoo had more than 195 million unique U.S. visitors from desktop computers in December, while Google came in second at 192 million. Microsoft was third with 175 million.
The three companies have long circled around each other in vying for the top spot. Google was on top until July 2013 until overtaken by Yahoo, which has been on top since.
Facebook was the highest-scoring social media site, coming in fourth on the list with 140 million visitors, while Amazon outdid all other e-commerce sites with 116 million visitors.