The Long Island's freight operations amounted to little more than branch lines which terminated more cars than they originated (68.0% of the loaded car miles were eastbound from the mainland vs. 32.0% westbound).

The two largest manufacturers, Grumman and Republic Aviation, had other means to ship their finished product. Accordingly, they ran short trains (21.3 cars per train) at slow speeds (8.1 MPH) not very far (average haul 18 miles). The average freight car moved only 2.3% of the time and 4.5 miles per day.

Potatoes & canned goods made up 86% of carloads originated plus whatever LCL cars were originated. These were primarily boxcar loadings on the LIRR. What was the source of cars for the LIRR's limited originated traffic? The owner, PRR, would be unlikely to provide empty boxcars if some other source was available.

Commodities terminated included coal, lumber, cement and iron & steel, the LIRR's four largest in 1947. The number of originated carloads could easily be accommodated in lumber boxcars after unloading and cleaning. Having to haul empty boxcars to Eastern Long Island caused the percent loaded of total car miles to hover around 50%.

Where was the source of that lumber? On railroads like the UP and SOU as well as others - these railroads whose boxcar traffic normally followed the boxcar ownership distribution on their own roads subject to a slight bias towards home road cars.

Branch lines having seasonal traffic like the DM&IR probably had many of the characteristics of the DM&IR in season while resembling the LIRR in the off-season. Included in this category would be branch lines in agricultural areas moving livestock, fruit and vegetables or grain after the harvest.