Before we leave this fascinating[?] look into frt car distributions, perhaps it's time for a brief and casual look at the logic with associated RR interchanges.

The Nelson/Gilbert theory says that the home road should be represented much higher than its % of the national fleet. Let's say 3 times the national number. The data that Tim Gilbert used includes that of 30 or so trains from the region Laramie-Green River WY in 1947. THe actual number was 87 UP box cars out of 777 total box cars or 11%. The UP national % in 1947 was 3.6% so 3 works pretty well. If you look at a RR map you'll notice that there's a junction at Granger, WY, where the UP goes to Pocatello, ID, and the Pacific Northwest. Other than that, UP tracks join SP at Ogden. There is a junction there with D&RGW as well. According to the theory, UP trains working east from Ogden should contain 11%-3.6%=7.4% more box cars than the national %. SP trains working west from Ogden should exhibit about the same. So...where do all the UP and SP box cars go? Where'd they come from? IOW, if trains containing about 3 times the national % of SP box cars are proceeding east on SP tracks west of Ogden I'm going to bet that they aren't going back down southwest to southern Cal on UP nor back west and up north on UP to the north Pacific. There are much shorter routes. I also doubt that many will transfer to the D&RGW. Westbound UP box cars might, indeed, travel on UP tracks south to S. Cal or to ID, OR and Wash. So, given the above, why would we doubt that SP box cars should show up on the UP WY trunk more than their national %?

There are similar locations where this might occur. For example, if the home road % rules, what about N&W and Southern between Knoxville, TN and Roanoke, N&W/NYC between points south of Columbus, OH and points north. For that matter, there must be many similar situations...such as GN/CB&Q or C&NW and the same for NP.

Mike Brock