Because I saw you post this in an older thread, I thought it might be a good idea to link to it here:
and tag Melinda Morang
This is should actually be pretty easy for you since your data is already in a format that lends itself well to this. You need to load all the origins and destinations into the Route layer's Stops sublayer. When doing the load, just map the "Route Name" field to the Stops sublayer's "RouteName" property. An individual route will be created for each unique RouteName.