Google's Android operating system topped out at 19 percent market share for the third quarter, while Apple iOS and BlackBerry are virtually tied for second place, according to fresh stats from Nielsen.
Nielsen said Apple's iPhone OS reached 28 percent share.
RIM BlackBerry OS, which just months ago commanded more than 40 percent of the U.S. smartphone market before the rivalry between iPhone and Android took wing, dipped to 30 percent market share.
The numbers are consistent with Nielsen's October report, when it said Android handsets totaled 32 percent of all smartphones sold from January to August.
Nielsen's numbers also arrived amid fresh Q3 numbers from NPD Group and Canalys, which found that Android paced the smartphone field in Q3, shipping on more than 40 percent of new smartphones.
What Nielsen keyed on for Q3 that comScore, NPD and Canalys didn't is that 28 percent of U.S. mobile subscribers now use smartphones thanks to the competition between RIM, Apple and Android.
"The growing popularity of smartphones like Apple's iPhone, RIM's BlackBerry devices and a variety of Google Android-based models on the market has accelerated the adoption rate," Nielsen said.
Also, 41 percent of consumers who purchased a new cell phone in the last six months picked a smartphone over a standard feature phone, up from 35 percent last quarter.
Nielsen's new stats are subject to some change over the next two months as the smartphone market glides through the holiday shopping season.
Apple's iPhone 4 has been the hottest-selling smartphone, while forthcoming Android devices such as the Motorola Droid Pro, Citrus and Spice, as well as T-Mobile's myTouch 4G and G2, could appeal to others.