Sort your customer database by zip code which will allow your sales people to travel short distances and spend far less time driving and looking for new sales. Less travel time means more time in front of potential customers. Obviously the decision who to call on depends upon sales size but it helps when calls to make are short ones. Selling to everyone in a region is much easier and more fruitful than driving hours between sales calls. Give your sales representatives the entire customer listing and mandate that customers once assigned obviously are then off limits to others. Your reps may want the list sorted by city if that is desirable. Give it to them in the manner that makes sense for your firm.