To move the Georgia peach crop the Southern Railway would need about 3,000 refrigerator cars. The shipments occupy about six weeks, beginning about the middle of June. The Pere Marquette Railroad moves about 2,000 carloads of fruit under refrigeration from Michigan points mostly in September and October, and would need about 1,000 cars for the work. These and other roads might well hesitate to invest the sums required to provide expensive equipment when it would have to be idle the greater part of the year; but this is easily done by a car company whose cars can be employed in the orange trade from California and Florida in the winter, in the Georgia peach traffic in June and July, and in the Michigan and New York fruit business during the fall.[263] The railroads began long ago[264] and still continue paying mileage rates for the use of stock cars, tank cars, and refrigerator cars, the three chief kinds of private cars. This would be all right if the mileage rate were fair, but serious injustice results when the mileage is so great as to give the owners of the cars a practical rebate of large amount on all their shipments in such cars, as is the case with all three classes of cars above named,[265] and especially with the refrigerator cars of the Armour Car-Lines which are operated in the interest of the Beef Trust. The railroads allowed at first a mileage rate of ¾ of a cent a mile when the car was loaded. After a little the car companies got the roads to pay the mileage on the cars both ways, loaded or empty. The mileage rate on refrigerator cars was raised from ¾ of a cent to 1 cent over most of the territory west of Chicago and St. Louis, and the 1 cent rate also applies to the movement of refrigerator cars between Chicago and New England via Montreal.[266] From Chicago to New York over the Vanderbilt lines is about 1,000 miles; so the mileage on a refrigerator car amounts to $7.50 each way, or $15 for the trip. The car companies have secured various concessions from the railroads besides the payment of mileage loaded or empty. They require the railroads to run their cars at high speed in special trains. The average run of the freight cars owned by the leading railroads is 25 miles a day. The average run of the private tank cars (Standard Oil mostly) is 66 miles, private stock cars 72 miles, refrigerator cars 108 miles, and refrigerators operated in the beef trade 135 miles per day.[267]