Secondary rail market prices for guaranteed grain service provide insight regarding U.S. rail service available to grain shippers. This analysis investigates alternative market information that may enhance indicators offered to gauge current and expected rail grain service levels. Regression analysis is used to assess the relevance and relationships of alternative rail grain service measures and market parameters. Findings add to the current knowledge base used for interpreting market parameters as indicators in current and expected rail grain service. Given the derived demand nature of transport, the relevance of demand variables such as manufacturing orders and outstanding grain sales is not surprising. In addition, more specific rail capacity measures such as average grain train speed and system dwell time also offer valuable rail grain service information. Although relationships are largely expected, the analysis offers new insight regarding the relative value of alternative secondary data sources as indicators in current and future rail grain service.