From the Document: "Since 1938, the Fair Labor Standards Act (FLSA, 29 U.S.C. §206) has required that certain workers be paid a minimum wage. Since then, Congress has raised the minimum wage rate 22 times, from $0.25 per hour in 1938 to its last increase on July 24, 2009, to $7.25. (P.L. 110-28 increased it from $5.15 to $7.25 in three steps beginning in 2007). Currently, the FLSA covers most, but not all, enterprises and private and public sector employees. Certain employers and employees are exempt from all or parts of the FLSA minimum wage provisions, either because they do not meet individual or enterprise coverage criteria or through specific exemptions included in the act."
CRS In Focus, IF11282
Congressional Research Service: https://crsreports.congress.gov/