comScore:

173 million people in the U.S. owned smartphones (71.8 percent mobile market penetration) during the three months ending in July, up 3 percent since April. Apple ranked as the top OEM with 42.4 percent of U.S. smartphone subscribers (up 1 percentage point from April). Samsung ranked second with 28.4 percent market share (up 0.7 percentage points), followed by LG with 6.4 percent, Motorola with 5.7 percent and HTC with 4.7 percent.

That’s a pretty significant lead for Apple and they are outpacing Samsung in terms of growth.