Up from one-third in May 2011.
New research from Pew Internet says 46 per cent of adults in the US now own a smartphone, up from 35 per cent last May. This means that smartphones have overtaken feature phone ownership, which sits on 41 per cent.
As for the OS types being used, one-fifth are using Android and 19 per cent are using iPhones, which is up from 15 per cent and 10 per cent in May 2011, respectively.
Not all firms received a growth though, with BlackBerry use falling from ten per cent to six per cent.
All demographics demonstrated a rise in smartphone adoption, regardless of gender, age, race and income. However, the least dramatic changes came from those aged 65+, rising by just two percent, while the biggest changes came from 18-24 year olds and those living in rural areas.
Perhaps the boost to rural adoption was aided by key rollouts of LTE in America, aiding the strength of operator signal.
Additionally, confusion over the term 'smartphone' has decreased from 14 per cent to just eight per cent of mobile owners that remain baffled.