Google's platform, however, dominates worldwide market.
During the 12 weeks ending on October 28, Apple's iOS accounted for a 48.1 percent smartphone market share in the United States, with Google's Android settling for 46.7 percent.
However, elsewhere, iOS isn't as popular as its fellow ecosystem. According to research firm Kantar Worldpanel ComTech, Android was running on 73.9 percent of all smartphones in Germany during the period in question. Android dominated in Spain as well with a 81.7 percent share.
Apple's success in the U.S., meanwhile, was due to the iPhone 5, Kantar said. The company noted that the last time iOS had a higher market share than Android was when the iPhone 4S launched last year.
While other reports suggest otherwise, Apple has benefited greatly from customer loyalty. Kantar said 92 percent of consumers who own an iPhone will upgrade to another Apple smartphone.
As for overall worldwide share in the smartphone market, Android accounts for 75 percent (90 percent in China), while iOS settles for 14.9 percent.