Thanks to growing adoption of the iPhone and other smart mobile devices, an increasing number of Americans are logging onto WiFi networks to access the internet on the go.
Growth is heaviest in the heavily metropolitan West and Northeast sections of the country, together with Texas. California led the way with 18 percent of usage, followed by New York with 14 percent and Texas with 8 percent.
The findings come from mobile ad network AdMob's Mobile Metrics Report.
Worldwide mobile ad requests increased 8 percent month over month in January to 6.8 billion, led by double digit growth in Western Europe and Asia, but ad requests remained flat to negative growth in most of North America.
Overall mobile traffic from Western Europe increased 132 percent over the past year to total 550 million ad requests last month, with Spain and Italy showing the most robust growth.
Reflecting patterns in the US, the iPhone is now the Western Europe's device of choice for accessing the mobile internet, accounting for an impressive 21 percent share of total ad requests.