Snapchat now has more than 60 million daily active users in North America – or about a third of what Facebook has – as it seeks to tap into the world’s most lucrative advertising market, chief strategy officer Imran Khan told an advertising conference in New York.

The 60 million figure compares with Facebook’s 175 million daily active users in the region. Twitter, which doesn’t report a daily active user base, has 66 million monthly users in the US, virtually unchanged for six quarters.

The advertising market in the US and Canada has driven the bulk of sales at Facebook and Twitter, and will probably do so for Snapchat, too. Facebook’s average revenue per user in that market is US$12.43 , compared with a $3.32 global average.

Closely held Snapchat is building out its business model ahead of an eventual initial public offering.