First off, congratulations and good luck in that first round!
Now, North America is pretty huge, with 30+ offices! Why don't you narrow down the list yourself a bit more. Surely there are regions (east coast US, southern US, Western Canada/US, etc.).
Then, can you also narrow down your request? I.e. what, specifically do you want to know?
This is a good learning as a consultant by the way...never boil the ocean!
Finally, this is a great networking "excuse". This information can be asked + understand through networking calls.