49 CFR 1241.1: Common carriers.

All common carriers subject to the provisions of Part I of Interstate Commerce Act, as amended, and the owners of all railroads engaged in interstate commerce as therein defined, are hereby required hereafter to file in the office of the Board on or before the 31st day of March in each year, reports covering the period of 12 months ending with the 31st day of December preceding said date, giving the particulars heretofore called for in the annual reports required by the Board of said carriers and owners of railroads.