Google's Android has bitten off a 50 percent chunk of the U.S. smartphone market, according to the latest stats from ComScore.
Over the three months from December through February, Android carved out an average 50.1 percent share, a leap of 17 points from the same period in 2011 and 3.2 points from the prior three-month period.
In second place, Apple's iOS grabbed a 30.2 percent share, inching up 1.5 points from the previous three months. Combined, those numbers gave iOS and Android a collective share of more than 80 percent.
As a result, other mobile platforms aren't faring as well.
RIM's U.S. market share fell more than three points to 13.4 percent, according to ComScore. Microsoft saw its share for Windows Mobile dip more than a point to 3.9 percent. And Nokia's Symbian remained flat with a market share of just 1.5 percent.
Overall, more than 104 million people in the United States owned smartphones during the three months ending in February, up 14 percent over the prior period.
Among all mobile-phone makers (smartphones and feature phones), Samsung retained the highest market share in the United States, though flat. LG stayed in second place, despite losing a point since the prior period.
In third place, Apple enjoyed the highest growth among all manufacturers, with a 2.3 percent rise in market share. Motorola and HTC capped off the top five with shares of 12.8 percent and 6.3 percent, respectively.
Looking beyond just market share, Apple and Samsung hold a tight lock on the mobile industry, in terms of profitability, leaving little left for other vendors. Together, the two eked out 95 percent of all mobile-phone profits during the fourth quarter, according to Canaccord Genuity, with Apple grabbing 80 percent of that.
Android as a mobile OS continues to mow down the competition, while Apple and Samsung as handset makers do the same. That pattern is likely to continue to make life difficult for handset makers Research In Motion and Nokia, as well as mobile OS maker Microsoft, as they struggle to play catch-up in the competitive mobile marketplace.