Occupational staffing patterns changed radically over the 1910-2000 period in response to changes in the mix of goods and services produced and the methods used to produce them.
Professional, technical, and kindred workers rose from ninth largest to the largest occupation group. That group had the largest percent (and numeric) increase from 1910-2000, while the farmer and farm laborer groups had the largest percent (and numeric) decreases.
Five of the major occupation groups increased as a share of the total, while six declined. All of the ones that declined, except for private household workers, consist of occupations that produce, repair, or transport goods and are concentrated in the agriculture, mining, construction, manufacturing, and transportation industries. The five that increased are the so-called white-collar occupations, plus service workers, except private household.
In aggregate, the five groups that increased went from 24 percent to 75 percent of total employment, while the six groups that declined went from 76 percent of 25 percent over the 90-year period.
These data are from the Office of Occupational Statistics and Employment Projections. Find more information in "Occupational changes during the 20th century," by Ian D. Wyatt and Daniel Hecker, Monthly Labor Review, March 2006.
Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Occupational changes: then and now at https://www.bls.gov/opub/ted/2006/apr/wk1/art04.htm (visited August 18, 2022).