We are trying to create districts or working areas for our employees so that they have roughly the same amount of employees in each

I have all the addresses but i'm looking for something that will draw district boundaries preferably something just built on top of google earth or google maps

any ideas

Platform either web or Windows (7-8-10)
I would be willing to pay but prefer free
In this case I am looking for United States

the data is small enough (few hundred rows) I would change it to match the softwares requirement