The summer travel rush has been good to HotelTonight, the last-minute hotel booking service: the site today announced that it has now had 3 million downloads of is mobile app, and it is marking the occasion by continuing its scaling efforts in the U.S. and UK — where it spearheaded its international push in June, fuelled by its latest $23 million investment.

The company is now covering hotel bookings in Birmingham, Edinburgh, Glasgow and Liverpool, as well as St. Louis, Charlotte, Pittsburgh and Nashville.