Does the "Third and 30" achievement track across multiple saves?

The requirement for the "Third and 30" achievement in Saints Row: The Third says Spend over 30 hours in Steelport. If I have 20 hours on one save file and 10 on another, will I get the achievement? Or does this have to be completed with 30 hours in on one save file?

A more accurate description of this achievement would be:

Get the clock on your phone's stat screen and on the save game list to read more than 30 hours.

I stopped playing at 29 hours 50 minutes or so and loaded a new game, waited 10 minutes, and nothing happened. I also loaded an older save on my "main" game and it didn't pop there either. The only thing that unlocked it was when the clock on the phone rolled over past 30.

Note that this means that any time during which the game is paused does not count towards this. Co-op time does though.