12 INDUSTRIAL REVOLUTION AND WAGES was termed the Central Competitive Field, made up of [llinois, Indiana, Ohio and Western Pennsylvania. The rates of pay in other mining areas were related to these ruling rates, varying according to comparative physical factors, such as the thickness and character of the coal seams, and the ease or difficulty of mining coal. Wages and working conditions were, therefore, practically stand- ardized on a national basis, with due allowance for vari- ations in local conditions of mining. On the railroads, the highly organized engine and train crews, popularly known as “The Brotherhoods,” at first carried on relations with the individual railroads. After- wards, negotiations and collective bargaining developed according to geographical sections known as the East, Southeast and West, the railroads being grouped respect- ively for these designations as (1) North of the Ohio and Potomac and East of the Mississippi, (2) South of the Ohio and Potomac and East of the Mississippi, and (3) West of the Mississippi River. This geographical group- ing for industrial relations and the determination of wage- rates was brought about primarily through its acceptance by railway managements for the purpose of protecting their own interests. They found it expedient to have wages and working conditions standardized in certain areas, in order to nullify the tactics of the labor organiza- tions in playing one individual railroad against another for the purpose of establishing precedents for collective bar- gaining. Standardization was also strongly supported by the rail- way labor organizations. Before our entrance into the World War the unions of engine and train crews had effectively organized the “Eight-Hour Day Movement” on a national basis. At the same time, they were attempting