Drew.allen - I think that might be it!

I dumped the CASE data into a temp table and added a SELECT DISTINCT ADDRESS1, ADDRESS2 to get the distinct list and I think this works.  I used this query against the sample data I posted and it returns the same address sets as my ExpectedResults table.

I never would have thought to use < to compare.

Here's another challenge on this, should you all choose to accept it.....

What if there were additional columns in the table, such as City, Lat, and Lon for each record?  So expand the original table from TripID, Pickup_Address, Dropoff_Address to TripID, Pickup_Address, PickupCity, Pickup_State, Pickup_Lat, Pickup_Lon, Dropoff_Address, Dropoff_City, Dropoff_State, Dropoff_Lat, Dropoff_Lon.

I can't imaging that the < compare would still work here, would it?