Maryland Code, Public Utilities § 9-401

(b)(1) If a railroad company does not have sufficient cars to meet the demand to transport freight in carload lots, the railroad company shall distribute available cars to shippers that apply.

(2) Except for giving priority to transporting livestock or perishable property, a railroad company may not discriminate in any way, including preferences as to shippers, localities, or competitive or noncompetitive points, when supplying cars under this section.