Smartphones make up 10 per cent of all web traffic in the US, according to Monetates eCommerce Quarterly report for Q3, 2012 – thats up from 8.7 per cent in Q2, and just 6.1 per cent in Q1. By comparison, the international average is 5.7 per cent.

Smartphone conversion rate is 1.01 per cent, a figure which has been gradually falling since it peaked, at 1.2 per cent, in Q4 2011. The average order value on smartphone was $97.82 during the quarter, a slight increase on Q2 – though its worth noting that this again peaked in Q4 last year, at $119.74.

According to Monetate, Android devices have the highest conversion rate (1.09 per cent), though thats fallen from 1.23 per cent in Q2. iPhones, meanwhile, has remained more or less steady throughout 2012, with a conversion rate of 0.97 per cent in Q3.

Tablets make up 8.4 per cent of all web traffic, up from 7.2 per cent in Q2 and 6.1 per cent in Q1. The average order value on tablet devices is $96.84, and conversion rate is 3.1 per cent.

The iPad has held its position as the tablet with both the highest average order value ($97.87) and conversion rate (3.17 per cent).

The US state with the highest combined smartphone and tablet traffic is Maryland, with 21.2 per cent of its web traffic coming from a mobile device. Rounding out the top five are South Carolina (20.7 per cent) Georgia (20.4 per cent), Mississippi (19.9 per cent) and Texas (19.5 per cent).

The state where mobile has the lowest share of traffic is Iowa (11 per cent), followed by Vermont (12 per cent), Montana (12 per cent), Maine (12.3 per cent), and Wisconsin (12.5 per cent).

Interestingly, all of the top five – except Maryland – are southern states, whereas the states where mobile has the lowest share are all in the north of the country. That comes as something of a surprise, given the general perception of northern states as more cosmopolitan regions.