Has Facebook peaked? The number of active users in the U.S., Canada, the U.K., and several other countries declined this month, in some cases sharply. According to Inside Facebook, a research and marketing group, the number of active user in the U.S. declined by about 6 million last month. Canada lost 1.5 million. Some of the declines may be due to seasonal changes, such as college graduations, but Inside Facebook has found that growth usually slows to a halt after half a country’s population is on the site. Facebook continued to expand in relatively new markets, such as Brazil, India, and Indonesia.