Weekly grain cars loaded and billed data from the Surface Transportation Board's (STB) Rail Service Metrics. As part of their submission to the STB, railroads provide data broken out by state on the total number of grain cars loaded and billed. STB requests railroads include cars in shuttle service; dedicated train service; reservation, lottery, open and other ordering systems; and private cars. The reported cars are separated into three components: (1) total grain cars loaded and billed for shuttle service (or dedicated train service); (2) total grain cars loaded and billed for ordering systems other than shuttle (or dedicated train) service; and (3) the combined total (that is, the total grain cars loaded and billed for all ordering systems).

Grain includes the following Standard Transportation Commodity Codes (STCCs): 01131 (barley), 01132 (corn), 01133 (oats), 01135 (rye), 01136 (sorghum grains), 01137 (wheat), 01139 (grain, not elsewhere classified), 01144 (soybeans), 01341 (beans, dry), 01342 (peas, dry), and 01343 (cowpeas, lentils, or lupines).