Nielsen's August 2011 data revealed that Google was the most visited site with 176 million unique U.S. visitors.
"While all sites in the Top 10 saw an increase in unique U.S. visitors during the month, Amazon had the largest increase (5.9%) among the top sites increasing its rank to become the 9th most visited site during August 2011," revealed Nielsen.
Nielsen says, "Visitors to Facebook's website spent the most time on average, logging over 7 hours 45 minutes using the social network over the course of the month." AOL also increased the amount of time spent by average visitors on their site by over 25% during August.
Overall 215 million Americans were active on the Internet in August 2011, an increase of 1.2% compared to the previous month. Nielsen estimates 275 million Americans had access to the Internet during August 2011.
On average Americans spent over 30 hours online during August and visited 99 unique domains.