Apple shipped an estimated 17.7 million iPhones as "robust demand" for Internet connections on the move caused overall shipments of mobile phones to grow to 52 million in the United States, up four percent from the same three-month period in 2011.
"Apple has become the number one mobile phone vendor by volume in the United States for the first time ever," Strategy Analytics said.
"Apple's success has been driven by its popular ecosystem of iPhones and App Store, generous carrier subsidies, and extensive marketing around the new iPhone 5 model."
South Korea-based Samsung shipped 16.8 million mobile phones in the US in the quarter, seeing its share of the market increase five percent to 32 percent but "not enough to hold off a surging Apple," according to Strategy Analytics.
Samsung had been the number one mobile phone vendor in the US since 2008 and will "surely be keen to recapture that title," the research firm said.A separate survey highlighted Apple's top share of the smartphone market in the United States.
Industry tracker NPD Group said Apple held 39 percent of the US smartphone market, even though its lead narrowed over Samsung, which boosted its market share to 30 percent. A year earlier, Apple had 41 percent to 21 percent for Samsung, NPD figures showed.
"Even taking into account the tremendous sales growth of the Galaxy III and other Samsung smartphones, the iPhone is still king of the US-market hill," said NPD analyst Stephen Baker.
"In addition to strong US sales of iPhone 5, Apple has been bolstered by strong and continued demand for older, less-expensive iPhone models."
NPD said the iPhone 5 was the most popular smartphone in the US market in the past quarter, followed by the Samsung Galaxy S III.
The older versions of Apple's smartphone, the iPhone 4S and iPhone 4, were in third and fourth places, respectively, followed by Samsung's Galaxy S II, NPD said.