If you spend a significant amount of time in several cities, you can indicate so on your profile. At the top of Your Profile, you can see the current Primary Working Location for your profile.

To add or edit any additional working locations, click Edit next to your Primary Working Location, or click Edit next to Working Locations at the bottom of your profile. 

Each profile can have one primary working location and up to two additional working locations. When submitting your profile to a project on Casting Billboard, you do have the opportunity to choose your working location when customizing your submission.