Canalys data backs it up, with both putting Apple ahead of RIM in second place.
Google's Android OS took a 44% share of all new smartphones bought in the US last quarter, according to research from both NPD Group and Canalys.
NPD's stats show that Android's runaway success is hurting Research In Motion's BlackBerry OS more than iPhone, however.
In Q2, the research firm had Android in the lead with 33%, followed by BlackBerry with 28% and iPhone with 22%.
In Q3, it claims Android increased to 44%, and BlackBerry fell to 22%, allowing iPhone to overtake it by increasing its market share to 23%.
"Much of Android’s quarterly share growth came at the expense of RIM, rather than Apple," says NPD's Ross Rubin.
"The HTC EVO 4G, Motorola Droid X, and other new high-end Android devices have been gaining momentum at carriers that traditionally have been strong RIM distributors, and the recent introduction of the BlackBerry Torch has done little to stem the tide."
iPhone 4 was the most popular handset sold in the US in Q3, according to NPD - that's out of all phones, not just smartphones - followed by the BlackBerry Curve 8500 series, LG Cosmos, Motorola Droid X and HTC EVO 4G.
Canalys US smartphone market share figures for Q3 back up NPD's conclusions, although the exact details vary - these are based on shipments rather than sales.
It pegs Android's Q3 shipments in the US at 9.1 million, giving it a 43.6% market share. It's followed by iPhone (5.5 million - 26.2%) and BlackBerry (5.1 million - 24.2%).
Fourth-placed Windows Mobile is a long way behind with 0.6 million shipments and a 3% market share.