Source: U.S. Bureau of Labor Statistics
Wage and salary workers are workers who receive wages, salaries, commissions, tips, payment in kind, or piece rates. The group includes employees in both the private and public sectors but, for the purposes of the earnings series, it excludes all self-employed persons, both those with incorporated businesses and those with unincorporated businesses. For more information see http://www.bls.gov/cps/earnings.htm
The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LEU0254522300
U.S. Bureau of Labor Statistics, Employed full time: Wage and salary workers: Subway, streetcar, and other rail transportation workers occupations: 16 years and over [LEU0254522300A], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/LEU0254522300A, December 15, 2018.