Nearly 17 million US mobile subscribers used location-based ‘check-in’ services on their phones in March 2011, found a new study by comScore.

The study showed that users have done 12.7 million check-in on smartphones, representing 17.6% of the smartphone population.

The check-in service users, representing 7.1% of the entire mobile population, showed a high propensity for mobile media usage, including accessing retail sites and shopping guides. They also displayed other characteristics of early adopters, including a stronger likelihood of owning a tablet device and accessing tech news, when compared to the average smartphone user.

comScore mobile senior vice-president Mark Donovan said the ability to interact with consumers on micro-local level through special offers, deals and other incentives provides brands with the real-time opportunity to engage consumers through their mobile device.

The research firm said that of the 16.7 million people using check-in services on their mobile devices, 12.7 million (76.3%) did so via a smartphone device.

Android accounted for the largest share of check-in service users with 36.6% checking-in from an Android device, while 33.7% of users checked in from an iPhone. Apple had the highest representation relative to its percentage of the total smartphone market.

RIM accounted for 22% of check-in service users, while Microsoft, Palm and Symbian each accounted for less than 5%.

The study showed that more than 95% of check-in service users used their mobile browser or applications. Nearly 62% accessed news. Check-in user behavior was also consistent with that of traditional early adopters, with 40.3% of users accessing tech news and 28.2% owning a media tablet, both significantly higher than average.

Further, check-in service users also showed a high propensity for accessing retail-related destinations on their mobile devices. Nearly one-third of users accessed online retail sites on their mobiles, while one-fourth accessed shopping guides.

Check-in service users were also more likely to be exposed to mobile advertising, with nearly 40% recalling seeing a Web or app ad during the month, compared to just 27.5% of smartphone users.