Android matched iOS in U.S. OS market share, according to the monthly Mobile Mix report from Millennial Media. The report is based on impressions served on Millennial’s ad network, which currently reaches 68 million mobile users across the country.

According to the report, October was the first time that Android has tied with Apple’s iOS as the largest smartphone OS on the Millennial network, with an 8 percent increase month-over-month and 37 percent impression share, which ties Apple’s share.

Android ad requests grew 65 percent month-over-month, and since January, Android has now grown 2,182 percent.

Smartphone impression share overall increased 3 percent month-over-month and accounted for 61 percent of the mobile phone impression share in October. The company attributes the increase to the continued rapid consumer adoption of smartphones.

Feature phone impression share increased just 1 percent from the previous month and represented 28 percent of the smartphone, feature phone and connected device mix.

Mobile Mix also gauges device and OEM share. The iPod touch was included on the list of top mobile devices for the first time and was No. 3 (ahead of phones like the Motorola Droid). Still, Motorola became the No. 3 manufacturer and held a 15 percent impression share.

Two new Motorola Android devices, the Droid 2 and the Droid X, both made their entrance into the Top 30 Mobile Device list.