THE steam railroads of the United States operated 261,871 miles of track in 1925, and of this amount 236,- 849 fell to those rated as Class I railroads. Operating railways are officially divided into three classes, according to their gross operating revenue in 1919, and to Class I are assigned all roads with $1,000,000 or more of such revenue. As noted, they operate about nine-tenths of the total mileage and transact an even greater proportion of the business of all the railways. For these large and important railways detailed statistics of operation are available.
The railroads are large employers of labor. In December, 1927, the employees of Class I roads numbered 1,660,338 persons, of whom the greater part were wage earners coming within the purview of the present investigation.
For the study of earnings of railway employees the Interstate Commerce Commission furnishes abundant information in its monthly "Wage Statistics of Class I Steam Roads in the United States." These issues show the number of employees, the number of hours or days worked and the compensation paid, for 148 different classes of workers. Not only are the total compensation and the hours to which it applies given, but the same facts are published for the regular working hours, for overtime work at regular rates and for overtime work at special rates.
For the purpose of presentation in this volume the various occupations have been grouped. First of all there is a class numbering about sixty-eight different occupations, whose work indicates that they belong in the salaried rather than the wage earning class, and who are therefore disregarded in the computations made in this chapter. The remaining eighty occupations are divided into three main groups. Two of those, classified as "train and engine service" and as "skilled and semi-skilled shop labor," correspond to the skilled