For the first time, mobile devices have topped laptops in public Wi-Fi network usage, according to a Q2 2012 study by location-based mobile ad network JiWire. JiWire serves ads to devices accessing the web via 30,000 public Wi-Fi locations in North America, the company reports.

In Q2 2011, 70% of public Wi-Fi network traffic stemmed from laptops, while only 21% came from smartphones and 9% from tablets, JiWire finds. But one year changed everything. In Q2 2012, laptop traffic sunk to less than half, 48%, while smartphone traffic jumped to 35% and tablets to 17%.

“This represents a major milestone: Mobile devices are leading a category that has historically been considered laptop-centric, and in places like restaurants and shopping malls,” says Dee Dee Paeseler, director of strategic marketing at JiWire. “Now it becomes more about reaching the right audience in the right location with the right message.”

Mobile devices dominated the airwaves in shopping malls and restaurants. 50% of Wi-Fi traffic in shopping malls stemmed from smartphones, 37% from laptops and 13% from tablets, JiWire finds. 72% of Wi-Fi traffic in restaurants came from smartphones, 20% from laptops and 8% from tablets, the study says.

Though Google Inc.’s Android has a commanding lead in the mobile operating system race, JiWire finds that users of devices running Apple Inc.’s iOS—iPhones, iPads and iPod Touch devices—are far more interested in mobile ads. 80.5% of ad requests on JiWire’s mobile ad network came from iOS devices while only 15.9% came from Android devices. BlackBerry users accounted for a mere 2.1% and Windows Phone a pittance at 0.4%. 1.1% of ad requests came from devices running other mobile operating systems.

There are 114,036 public Wi-Fi networks in the U.S.—76% are paid, 24% are free, JiWire reports.