In the Build Up Method, you begin with all the sales territories using whatever sales territory criteria that you choose. This may be states, cities, or zip codes. You then begin to combine or build-up territories trying to equalize the workload. Often, this is done using sales force activities like optimal call frequencies. That is, how many times per year should a customer be called? Next, the sales manager determines what an average salesperson can handle in terms of workload factoring in such issues as travel time as well. After this, a sales manager draws territorial boundaries, such that each salesperson's workload is about the same. This can be done by trial and error, or by using computer allocation programs. As time goes on, it will be necessary to modify the territories as market conditions change.