Minimum wage in 1938 was 25 cents an hour, which is about $4 per hour in today’s money.
It was set by Franklin Delano Roosevelt in 1938 as part of the Fair Labor Standards Act (FLSA), which also established overtime pay, recordkeeping, and youth employment standards.
Since minimum wage was first introduced in the United States, it has been raised 22 times by 12 presidents. (As of this answer, May 16, 2019)