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Soft Coal, Hard ChoicesThe Economic Welfare of Bituminous Coal Miners, 1890-1930$

Price V. Fishback

Print publication date: 1992

Print ISBN-13: 9780195067255

Published to Oxford Scholarship Online: October 2011

DOI: 10.1093/acprof:oso/9780195067255.001.0001

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(p.224) (p.225) Appendix A Calculating Earnings for Workers in Coal Mining and Manufacturing

(p.224) (p.225) Appendix A Calculating Earnings for Workers in Coal Mining and Manufacturing

Source:
Soft Coal, Hard Choices
Publisher:
Oxford University Press

This appendix describes the basic methods for calculating hourly and annual earnings for coal miners and male manufacturing workers used in Table 6–1 and Tables A-1 and A-2. The data sources and methods of calculation are important to note because they may impart biases to comparisons of mining and manufacturing earnings.

Annual Earnings

The average annual earnings of full-time equivalent workers in Table 6–1 are roughly comparable for coal miners and manufacturing workers because they are constructed in a similar fashion. In several years, the Bureau of the Census published aggregate information on total wages paid to production workers and the number of workers on payrolls (including absentees) on or around the fifteenth of each month. Annual earnings per full-time equivalent worker are calculated by dividing total wages paid by the average number of workers on the payroll.1 The earnings for the census years are treated as benchmarks, and estimates for other years are determined by interpolating with evidence from other sources.

The coal mining estimates are annual earnings after the cost of supplies to the miner are deducted. The benchmark estimates for total wages paid in 1929, 1919, 1909, 1902, and 1889 come from the 1939 mining census, which reports them on a comparable basis.2 Table 6–1 shows two estimates for full-time annual earnings in coal mining based on substantially different estimates of average employment from surveys with similar, complete coverage of the coal industry.3 The Greenslade estimates are based on employment figures from the U.S. Geological Survey, the Census estimates on employment from the mining Census. Interpolations between benchmarks for both series are based on Greenslade’s work.

It is unclear which estimate is more accurate. The Census estimates for coal mining may be more comparable with the manufacturing estimates because the Census followed the same survey procedures in collecting employment data. Douglas and later Greenslade chose the Geological Survey employment estimates in their attempts to obtain time-series estimates of hourly earnings for three reasons.4 First, an extended strike in 1919 meant that strikers did not appear on the payrolls for some months. The Census average employment estimate was lowered because the survey recorded only the number of workers who showed up for work in each month, while the number of miners on the payroll before and after the strikes was much (p.226) greater.5 Second, the 1902 Census reduced the employment figures to a 300 workday year, which makes them incomparable with later years. As a result, annual earnings based on Census employment in Table 6–1 begin in 1909. Third, they felt that the Geological Survey estimates were adequate because they were described as representing “the number of men commonly dependent on the mine for employment. They represent the number ordinarily reporting for work when the mine starts, plus the absentees.”6

Greenslade’s estimate of annual earnings based on Geological Survey employment is a lower bound. The U.S. Geological Survey’s employment data overstates the relevant employment figure in two ways. The Geological Survey’s employment estimates include supervisory personnel and technical people, while Census data on total wages paid do not. Subtracting the supervisory personnel and technical people raises the estimate of average annual earnings by around 2 percent.7 Further, researchers for the Works Progress Administration in the 1930s discovered that when reporting to the U.S. Geological Survey, many mines reported the number of men on the payroll in December or January and not the average number for the year.8 Since December or January are typically months of high employment, the number employed in December or January overstates the true average for the year. If all mines had reported December employment rather than average employment, the U.S. Geological Survey’s estimates would have been roughly 4 percent too high in 1929, 8 percent too high in 1919, 9 percent in 1909, and 8 percent in 1902.9

Douglas calculated annual earnings per full-time equivalent worker for all manufacturing workers from Census data.10 Since coal miners were nearly all males, Douglas’s manufacturing earnings underestimate the manufacturing alternatives for miners by including the earnings of female workers. The manufacturing earnings in Table 6–1 are therefore Douglas’s estimates multiplied by 1.10, which is a rough estimate of the ratio of male earnings in manufacturing to the earnings of all workers in manufacturing.11 The annual earnings of farm laborers are based on the U.S. Department of Agriculture’s series on monthly wages without board with straight-line interpolations by Douglas.12

Hourly Earnings

The estimates of hourly earnings for the United States in Table 6–1 are based on the work of Greenslade for coal mining and Albert Rees for manufacturing. Greenslade (and earlier Douglas) calculated coal earnings and Rees calculated manufacturing earnings for 1890 to 1919 using the same procedure. They started with average annual earnings per full-time equivalent worker in the census years and interpolated between census years with data from reports of the state labor bureaus. They transformed annual earnings into daily earnings with state data on the average number of days that establishments operated. The daily earnings are converted into hourly earnings with data on full-time hours from various sources.13

Rees’s estimates for manufacturing workers include all workers, male and female. Nearly all coal miners were males, so their true opportunity cost wage in manufacturing was the wage for male workers. I calculated male annual earnings by multiplying Rees’s estimate for all workers by 1.10. The 1.10 scalar is discussed more fully in note 11 and assumes that the ratio of female to male earnings was 0.558 and that females were 20 percent of the manufacturing work force. The resulting estimate of male manufacturing earnings is probably biased upward. Ratios of female to male hourly earnings from the National Industrial Conference Board range from 0.67 in 1914 to 0.59 in 1923, which would lower the male scalar to 1.07 and 1.089. A source of downward bias in the manufacturing estimates might be the use of full-time hours per day rather than actual hours per day. However, Rees found no downward bias when he checked his estimates against other benchmarks.14

(p.227)

Table A-1. Average Hourly Earnings for Male Manufacturing Workers Estimated from Census Data and Coal Wage Workers from Census and Geological Survey Data by States in Current Dollars

State

1929

1919

1909

1904

1902

1899

United States

    Manu.

58.7

52.5

20.5

18.6

18.2

16.1

    Coal

64.5

69.7

27.7

26.7

24.2

18.5

Alabama

    Manu.

37.1

40.3

14.2

13.6

10.6

    Coal

46.0

54.8

20.7

19.6

Colorado

    Manu.

56.7

54.8

26.6

25.9

23.3

    Coal

86.5

78.0

29.7

26.1

Illinois

    Manu.

66.4

56.1

23.1

21.4

18.1

    Coal

85.8

80.7

38.1

29.0

Indiana

    Manu.

59.4

51.9

19.8

18.2

16.0

    Coal

86.3

78.5

37.4

29.1

Kentucky

    Manu.

50.4

43.6

16.6

16.1

13.5

    Coal

57.0

64.7

22.8

17.1

Ohio

    Manu.

65.6

58.2

21.6

19.6

16.7

    Coal

59.7

73.2

31.5

26.7

Pennsylvania

    Manu.

62.3

57.1

21.6

19.6

17.6

    Coal

64.8

68.9

33.3

24.4

Tennessee

    Manu.

42.4

39.6

14.7

14.7

12.0

    Coal

41.9

46.0

20.2

17.0

Virginia

    Manu.

45.5

46.0

14.2

13.9

12.0

    Coal

49.2

56.1

19.8

11.0

West Virginia

    Manu.

59.3

54.1

19.4

18.3

14.1

    Coal

54.5

69.1

22.1

19.4

Sources: Coal hourly earnings are average annual earnings from Table A-2 divided by average work hours, which are the product of average days worked at the mine and the average length of the work shift. Days worked and average length of work shift in each state are from U.S. Geological Survey (after 1922, U.S. Bureau of Mines), Mineral Resources of the United States, Nonmetals, various years. Male manufacturing hourly earnings are average annual earnings from Table A-2 divided by the national average for hours worked from Rees, “New Measures of Wage-Earner Compensation,” pp. 3, 19; and Rees, Real Wages, p. 33. For 1929 I determined the national average for hours worked by dividing Rees’s estimate of hourly earnings into the annual earnings reported by Rush Greenslade, “The Economic Effects of Collective Bargaining in Bituminous Coal Mining,” (Ph.D. dissertation, University of Chicago, 1952, p. 49.

(p.228)

Table A-2. Average Annual Earnings for Male Manufacturing Workers Estimated from Census Data and Coal Wage Workers from Census and Geological Survey Data by States in Current Dollars

State

1929

1919

1909

1904

1902

1899

United States

    Manu.

1,433

1,257

   563

   534

   478

    Coal

1,142

1,097

   498

   464

   490

   379

Alabama

    Manu.

   912

   967

   395

   381

   305

    Coal

   938

1,054

   542

   477

Colorado

    Manu.

1,394

1,313

   736

   721

   621

    Coal

1,302

1,423

   817

   671

Illinois

    Manu.

1,631

1,345

   637

   597

   523

    Coal

1,215

1,033

   580

   525

Indiana

    Manu.

1,461

1,243

   548

   507

   462

    Coal

1,187

   930

   562

   479

Kentucky

    Manu.

1,239

1,046

   459

   448

   390

    Coal

1,026

1,000

   404

   329

Ohio

    Manu.

1,612

1,394

   597

   547

   483

    Coal

   963

   962

   526

   428

Pennsylvania

    Manu.

1,531

1,369

   597

   546

   507

    Coal

1,197

1,211

   707

   531

Tennessee

    Manu.

1,041

   950

   406

   409

   347

    Coal

   787

   755

   454

   367

Virginia

    Manu.

1,119

1,103

   391

   387

   347

    Coal

   983

1,119

   416

   321

West Virginia

    Manu.

1,458

1,296

   537

   512

   407

    Coal

1,204

1,117

   509

   381

Sources: Manufacturing data for 1904 and 1899 are total wages paid to men sixteen and over divided by the average number of men employed sixteen and over from U.S. Bureau of the Census, Census of Manufactures, 1905, Part I (Washington, DC: U.S. Government Printing Office, 1907), pp. xxxv, lxxi–lxxiii. The census did not report the total wages paid to males and females separately after 1905.1 estimated male earnings by calculating the ratio of earnings for all workers to earnings for males for 1909, 1919, and 1929 using the following formula: Wt/Wm = (1 − p) + p Wf/Wm, where Wt, Wm, and Wf are the average annual earnings for all workers, male workers, and female workers and p is the percent of the manufacturing workforce that is female. I assumed that (Wf/Wm) was equal to the ratio of male to female wages in either 1904 or 1899, whichever resulted in a larger estimate of the male wage. Data for Wt, (Wages total, divided by production workers) for the United States after 1904 come from U.S. Bureau of the Census, Census of Manufacturers: 1947, Volume I, General Summary (Washington, DC: U.S. Government Printing Office, 1950), p. 27. Data for p for the United States come from U.S. Bureau of the Census, Fifteenth Census of the United States, Manufacturers: 1929, Volume I, General Report (Washington, DC: U.S. Government Printing Office, 1933), p. 42. For the states after 1904, Wt and p are from U.S. Bureau of the Census, Fifteenth Census of the United States, Manufactures: 1929, Volume III, Reports by States (Washington, DC: U.S. Government Printing Office, 1933).

For coal mining annual earnings I followed Douglas and Greenslade and divided the total earnings paid to coal workers reported by the Bureau of the Census by the number of coal workers reported by the U.S. Bureau of Mines and the U.S. Geologic Survey. Total Wages in thousands for 1919, 1929 from Wages column, p. 256 in U.S. Bureau of the Census, Fifteenth Census of the United States, Mines and Quarries, 1929: General Report and Reports for States and for Industries (Washington, DC: U.S. Government Priting Office, 1933). Total Wages in thousands for 1909: Take gross wages column from U.S. Bureau of the Census, Thirteenth Census of the United States, Mines and Quarries, 1909, Volume XI (Washington, DC: U.S. Government Printing Office, 1911), p. 206, and multiply it by the ratio of Wages of production and development workers for 1909 from 1954 Census for the U.S. to the Wages for the U.S. from the 1909 Census (approx. 0.95). This eliminates miner’ purchases of supplies, explosives, oil, and blacksmithing from the wages. Total Wages in thousands for 1902 are from U.S. Bureau of the Census, Special Reports: Mines and Quarries, 1902 (Washington, DC: U.S. Government Printing Office, 1905), pp. 709–13. Employment for 1929, 1919, 1909, 1902 is from U.S. Geological Survey (after 1922 U.S. Bureau of Mines), Mineral Resources of the United States, Part II, Nonmetals, various years.

The hourly earnings of hired farm workers are based on U.S. Department of Agriculture surveys of farmers. The hired worker?’ earnings probably underestimate the coal worker’s agricultural alternative. Hired workers represented less than one-fourth of the agricultural work force and included migrant workers and some women. However, Greenslade notes that hired workers are not clearly separate from farm operators and family workers. Farm operators at times worked for wages on other farms.15 We know that some workers moved back and forth between the mines and their family farms. Comparisons of coal earnings and earnings for hired farm labor at worst show the relative opportunities for a farmer choosing supplemental employment.

Greenslade’s estimates of coal hourly earnings in Table 6–1 start with his estimates of average annual earnings for full-time equivalent workers. He divided annual earnings by the U.S. Geological Survey’s estimates of days the mine tipple operated to obtain daily earnings.16 Hourly earnings are daily earnings divided by the standard length of the work shift. The resulting estimates of coal hourly earnings are biased in different directions at each stage of the calculation. First, as noted in the section on annual earnings, Greenslade’s estimates of coal annual earnings are biased downward, possibly by as much as 10 percent. Second, hourly earnings might be slightly understated by an overstatement of days worked. The U.S. Geological Survey’s inquiry about days worked concerned the number of days the mine tipple operated, which Greenslade felt understated days worked, because some maintenance work was performed when the tipple did not operate.17 Although daymen, workers paid by the day, worked roughly 120 percent of tipple time in 1920 and 1921, tonnage men, who were paid piece rates, worked only about 85 to 90 percent of tipple time. Weighting the percent of tipple time worked by each group by their share of the work force (tonnage men were 65 percent of (p.229) the work force in 1920), coal workers worked 97 percent to 100.5 percent of tipple time.18 Earlier, when the percentage of daymen was lower, tipple time probably overstated working time more. Third, the standard length of shift may slightly understate the time miners spent working and travelling to workplaces in the mine, slightly overstating earnings per hour. During the 1920s the standard shift reported by the U.S. Geological Survey was 8.07 hours. The U.S. Bureau of Labor Statistics found that coal workers actually spent 8.1 hours in 1922 and 8.4 hours in 1929 in the mine either working or travelling to workplaces.19

After summing all the biases, comparisons of hourly earnings of coal miners and male manufacturing workers are likely to be biased against finding coal earnings to be high. The coal earnings series probably slightly underestimates coal hourly earnings, while the manufacturing series slightly overestimates male manufacturing earnings.

(p.230)

Table A-3. Average Annual Earnings Per Full-Time Equivalent Worker and Hourly Earnings for Coal Workers in 1967 Dollars

Annual Earning

Year

Greenslade

Five-Year Average

Hourly

1890

1504

0.667

1891

1396

0.626

1892

1456

0.663

1893

1419

1324

0.696

1894

1123

0.658

1895

1228

0.632

1896

1128

0.588

1897

1080

0.552

1898

1264

1348

0.680

1899

1516

0.740

1900

1752

0.852

1901

1860

0.948

1902

1885

0.931

1903

1922

1840

0.981

1904

1719

0.989

1905

1815

1.000

1906

1933

1.056

1907

2074

1.030

1908

1726

1896

1.041

1909

1844

1.026

1910

1904

1.021

1911

1896

1.046

1912

2045

1.066

1913

2061

1932

1.034

1914

1761

1.050

1915

1898

1.089

1916

2260

1.141

1917

2516

1.247

1918

2672

2466

1.322

1919

2118

1.346

1920

2765

1.560

1921

2056

1.713

1922

2060

1.799

1923

2593

2212

1.800

1924

2180

1.576

1925

2173

1.377

1926

2362

1.362

1927

2058

1.331

1928

2144

2145

1.310

1929

2226

1.277

Sources: See Table 6–1. Deflated to 1967 dollars with the BLS consumer price index for all goods, series E-135 from U.S. Bureau of the Census, Historical Statistics of the United Stales, Colonial Times to 1970 (Washington, DC: U.S. Government Printing Office, 1975), p. 211.

(p.231)

Table A-4. Index of Greenslade Estimate of Coal Hourly Earnings Deflated by Different Measures of the Cost of Living (1914 = 100)

Earnings Deflated by

Cost of Living Indices

Year

BLS CP1

Douglas

Rees

BLS CPI 1967 = 100

Douglas 1890–99 = 100

Rees 1914 = 100

1890

0.63502

0.62596

27.0

  91

1891

0.59622

0.73602

0.58132

27.0

101

  92

1892

0.63150

0.77193

0.62248

27.0

102

  91

1893

0.66325

0.82696

0.66104

27.0

100

  90

1894

0.62648

0.77544

0.62923

26.0

  97

  86

1895

0.60200

0.71649

0.59524

25.0

  97

  84

1896

0.56009

0.65314

0.55380

25.0

  99

  84

1897

0.52580

0.60702

0.52616

25.0

100

  83

1898

0.64772

0.74778

0.64816

25.0

100

  83

1899

0.70488

0.79780

0.70535

25.0

102

  83

1900

0.81156

0.88389

0.80244

25.0

106

  84

1901

0.90300

0.96527

0.88235

25.0

108

  85

1902

0.88659

0.95900

0.89049

26.0

111

  86

1903

0.93490

1.00487

0.95296

27.0

116

  88

1904

0.94195

1.02126

0.94937

27.0

115

  89

1905

0.95254

1.03274

0.96003

27.0

115

  89

1906

1.00545

1.05347

1.00211

27.0

119

  90

1907

0.98076

0.97051

0.93590

27.0

126

  94

1908

0.99134

1.02152

0.96657

27.0

121

  92

1909

0.97723

1.00697

0.96328

27.0

121

  91

1910

0.97295

0.98283

0.95270

28.0

128

  95

1911

0.99676

0.97638

0.97602

28.0

132

  95

1912

1.01494

1.02195

1.00809

29.0

133

  97

1913

0.98461

0.98569

0.98133

29.7

137

  99

1914

1.00000

1.00000

1.00000

30.1

139

100

1915

1.03714

1.07057

30.4

136

1916

1.08653

1.10115

32.7

149

1917

1.18819

1.17708

38.4

179

1918

1.25878

1.20258

45.1

218

1919

1.28169

1.24125

51.8

247

1920

1.48595

1.43957

60.0

286

1921

1.63139

1.64147

53.6

246

1922

1.71342

1.73451

50.2

229

1923

1.71494

1.72940

51.1

234

1924

1.50136

1.51699

51.2

234

1925

1.31178

1.32511

52.5

240

1926

1.29760

1.31778

53.0

241

1927

1.26760

52.0

1928

1.24777

51.3

1929

1.21620

51.3

Sources: For Greenslade’s estimate of coal hourly earnings see Table 6–1. All deflated earnings are converted to 1914 = 100 for ease of comparison, BLS CPI is the BLS consumer price index for all goods in 1967 dollars, series E-135; Douglas’s estimate of the cost of living is series E-185, 1890–99 = 100; and Rees’s estimate of the cost of living is series E-186. All are from U.S. Bureau of the Census, Historical Statistics of the United States, Colonial Times to 1970 (Washington, DC: U.S. Government Printing Office, 1975), p. 211. Correlations between the deflated earnings are 0.9908 between the CPI-denated and Douglas-deflated earnings and 0.997 between the CPI-deflated and Rees-deflated earnings.

(p.232) (p.233)

Notes:

(1) . The average number of workers for the year was calculated by summing the number of workers each month and dividing by 12.

(2) . U.S. Bureau of the Census, Sixteenth Census of the United States, Mineral Industries, 1939 (Washington, DC: U.S. Government Printing Office, 1944), p. 230.

(3) . The estimates of total output from the surveys by the Geological Survey and the Census are within 1 percent of each other, as are their estimates of total coal revenue.

(4) . Greenslade improved on earlier estimates by Paul Douglas by using information not available to Douglas in 1930. Douglass based his calculations for the 1909 benchmark year on the gross wages that were reported, although information in other census years were for wages net of the cost to the miner of supplies. The Census of 1939 later translated the 1909 figure into net wages paid. For the 1920s, Greenslade used alternative interpolations that could make full use of information throughout the decade, whereas Douglas was forced to stop in 1926. Rush V. Greenslade, “The Economic Effects of Collective Bargaining in Bituminous Coal Mining?” Ph.D. dissertation, University of Chicago, 1952, p. 38 fn. 3, 42; Paul Douglas, Real Wages in the United States, 1890–1926 (Boston, MA: Houghton Mifflin Company, 1930), pp. 343–58.

(5) . The anthracite strike of 1902 also created a similar problem for anthracite employment estimates. Bituminous coal also experienced a strike in 1902 but not of major proportions.

(6) . Douglas, Real Wages, pp. 344–45, quoting F.G. Tryon.

(7) . Greenslade, “Bituminous Coal?” pp. 30, 34. In 1902 superintendents, foreman, managers, surveyers, and others accounted for 2.64 percent of all mine employees. U.S. Bureau of the Census,Special Reports, Mines and Quarries, 1902 (Washington, DC: U.S. Government Printing Office, 1905), p. 709.

(8) . Greenslade, “Bituminous Coal?” p. 35

(9) . The percentage figures are based on the ratio of December employment to average employment for the year as reported in the Fifteenth Census of the United States, Mines and Quarries, 1929, General Report and Reports for States and for Industries (Washington, DC: U.S. Government Printing Office, 1933), p. 284 and U.S. Bureau of the Census, Special Reports, Mines and Quarries, 1902, pp. 709–10.

(10) . Albert Rees offers alternative estimates of annual earnings in manufacturing, but they were designed primarily to calculate hourly earnings. His estimates were generally about 1 percent less than Douglas’s. See Stanley Lebergott, Manpower in Economic Growth: the American Record Since 1800 (New York: McGraw-Hill Book Company, 1964), p. 484, note 2.

(11) . The Bureau of the Census reported the total wages paid production workers and total production workers separately for male and female adult workers in 1899 and 1904, but not for later years. In both years the ratio of annual earnings for adult males to annual earnings for all adult workers in manufacturing was slightly less than 1.10. The figure is relatively low because females accounted for only about 20 percent of manufacturing workers, although the ratio of female to male annual earnings in manufacturing was 0.559 in 1904 and 0.568 in 1899. I calculated the ratio of all worker?’ earnings to male earnings in manufacturing for 1909, 1919, and 1929 using the following formula

Appendix A Calculating Earnings for Workers in Coal Mining and Manufacturing

where Wt, Wm, and Wf are the average annual earnings for all workers, male workers, and female workers and p is the percent of the manufacturing workforce that is female. The percent female was 21 percent in 1929, 20.1 percent in 1919, and 20.6 percent in 1909 U.S. Bureau of the Census, Fifteenth Census of the United States, Manufactures: 1929, Volume I, General Report (Washington, DC: U.S. Government Printing Office, 1933), p. 42. Using the 0.559 ratio of female to male earnings in 1904 for Wf/Wm and taking the inverse of Wt/Wm, the ratio of male average annual earnings to average annual earnings for all workers was 1.102 in 1929, 1.097 in 1919, and 1.0996 in 1909. Given the constancy of this ratio over time it seemed reasonable to multiply the average for all earnings by 1.10 to get the measure for male earnings.

The 1.10 scalar may be an upper bound. The female-male ratio of weekly earnings in manufacturing from the National Industrial Conference Board ranged from 0.568 to 0.62 between 1914 and 1929; the female-male ratio for hourly earnings was 0.67 to 0.59 over the same period. These ratios of male to female earnings would have led to scalars less than 1.10. Ada Beney, Wages, Hours, and Employment in the United States 1914–1936, National Industrial Conference Board Studies Number 229 (New York: National Industrial Conference Board, 1936).

The annual earnings estimates for coal mining and manufacturing also included the earnings of children sixteen and under. This hinders the manufacturing-mining comparisons only slightly. Children composed 2.9 percent of manufacturing employment in 1904, 2 percent of coal employment in 1902. U.S. Bureau of the Census, Census of Manufactures, 1905, Part I (Washington, DC: U.S. Government Printing Office, 1907), pp. xxxv, lxxilxxiii; U.S. Bureau of the Census, Special Reports: Mines and Quarries, 1902, pp. 709–13. Both percentages declined over the next twenty years.

(12) . Douglas, Real Wages, p. 186. Annual earnings are twelve times monthly wages without board.

(13) . Manufacturing estimates for 1890 to 1914 are from Albert Rees, Real Wages in Manufacturing, 1890–1914, National Bureau of Economic Research Number 70 (Princeton, NJ: Princeton University Press, 1961), pp. 4, 23; after 1914 from Albert Rees, “New Measures of Wage-Earner Compensation in Manufacturing, 1914–57?” National Bureau of Economic Research Occasional Paper 75, 1960, p. 3. Rees argues that his estimates of hourly earnings are more comprehensive than Paul Douglas’s estimates in Real Wages. Douglas’s data give too high a weight to union earnings. Although the payroll industries data are superior to those for union industries, Douglas used information for “selected occupation?” peculiar to the industry. Therefore most unskilled workers and some semiskilled are excluded from his sample, an important consideration because most coal miners were unskilled or semiskilled.

(14) . Rees, Real Wages, pp. 28.

(15) . Greenslade, “Bituminous Coal?” p. 61.

(16) . After 1922 the U.S. Bureau of Mines took over the task of preparing and publishing Mineral Resources of the United States, the series that contains most of the coal mining data.

(17) . The inquiry was phrased: “Total number of full days mine (tipple) was in operation during the year. Parts of days should be reduced to equivalent in full days.‗ Quoted by Greenslade, “Bituminous Coal Mining?” pp. 34–35

(18) . Waldo Fisher and Anne Bezanson, Wage Rates and Working Time in the Bituminous Coal Industry, 1912–22 (Philadelphia: University of Pennsylvania Press, 1932), pp. 130–31.

(19) . The situation differed for tonnage workers and daymen. Tonnage workers in the 1920s worked between 7.2 and 7.5 hours per day in their workplaces after subtracting a half-hour for lunch. However, tonnage workers also spent roughly forty minutes a day in the mine travelling to and from their workplaces, raising the hours per day to 7.9 to 8.2. Daymen tended to work longer than the standard shift raising the average hours per day to the level in the text. U.S. Bureau of Labor Statistics, “Hours and Earnings in Bituminous Coal Mining, 1929?” Bulletin No. 516 (May 1930): 2–4; Greenslade, “Bituminous Coal Mining?” pp. 37, 102.