As this classifica

class 5, those that produce less than 10,000 tons. tion is made according to performance, not according to capacity, the number of mines in a given class is not constant from year to year. In 1918, for example, 821 mines were listed in class 1; in 1919, 550; in 1920, 701; in 1921, 482; in 1922, 416; and in 1923, 748. These fluctuations do not indicate a corresponding change from year to year in the number of mines having the acreage and the development that would enable them to produce annually 200,000 tons or more, but they do indicate that in a given year only the number of mines listed in class 1 were able to produce more than 200,000 tons.

MINES IN 1923

The number of mines active in each producing class varies with the condition of the coal market. A year of very high prices calls into operation thousands of small producers. Thus in 1920 the Geological Survey obtained information concerning 14,766 mines, of which 5,845 were wagon mines and country banks. In the depression of 1921 most of these small workings were closed. With the high prices that followed the strike of 1922, thousands of them reopened, and the total number of mines of all sizes of which the Survey could obtain records in that year was 14,150. By the end of 1922, however, the spot price was rapidly declining and the small operations were already beginning to close. Thus although the spot price stood at $4.38 in January, 1923, it soon fell to a level so low that many commercial mines found it difficult to operate, and by midsummer wagon-mine coal had again disappeared from the market. The lower prices of 1923 are revealed by the total number of mines recorded as in operation-11,715, as against 14,150 in 1922.

How these 11,715 mines were distributed among the five size classes recognized by the Geological Survey is shown in Table 49. Illinois continued to lead in the proportion of total output mined by class 1 operations. In that State 134 mines produced more than 200,000 tons in 1923; and they constituted 21.4 per cent of the total number of mines and contributed 74.8 per cent of the entire output of the State. West Virginia and Pennsylvania, though producing more coal, have relatively fewer mines of the largest size. In West Virginia class 1 mines constituted 6.8 per cent of the State total and produced 34.5 per cent of the output. The conditions of the Appalachian region, where in many places the beds now worked crop out above the water level and are readily accessible by slope and drift, favor small-scale development, whereas on the plains of the Middle West the necessity of sinking shafts puts a premium upon larger operations. Other States in which class 1 mines contributed the major portion of the output were Indiana, Montana, Pennsylvania, Utah, and Virginia. The average production of class 1 mines throughout the United States was 355,440 tons in 1923.

The immense number of small mines has given rise to an exaggerated idea of their importance as suppliers of coal. In comparison with most other years 1923 was favorable to their operation, yet as will be seen from Figure 42, although mines of class 5 constituted about 52 per cent of the total number, they produced but 2 or 3 per cent of the total output. In other words, even if all the 6,114 mines in class 5 were closed or permanently abandoned the potential output

of the country would be reduced by less than 3 per cent. Moreover, if all mines of class 4 (producing from 10,000 to 50,000 tons) should also be abandoned, only 15 per cent of the 1923 output would be withdrawn from the market. The closing of every operation in class 4 and class 5, though leaving only 24 per cent of the number of mines active in 1923, would leave 85 per cent of the production and presumably at least 85 per cent of the potential capacity of the country. It is therefore clear that elimination of the wagon mines would have practically no effect on the potential capacity and that the closing of even all mines producing less than 50,000 tons annually would fail to provide full-time operation for those remaining.

FIGURE 42.-Relative numbers and production of large and small bituminous-coal mines. Although the class 1 mines, with an individual output of 200,000 tons or over, constituted only 6.4 per cent of the total number, they produced 47.1 per cent of the total output in 1923. The very large number of small mines-52 per cent of the total number-furnished only 3 per cent of the output