The agency says the average minimum wage was $10.14 in 2013 and the 1975 wage, expressed in 2013 dollars, was $10.13.
Between 1975 and 2013, however, the minimum wage in 2013 dollars, varied, slipping to $7.53 in 1986 before rising to $8.81 in 1996.
Up to 2003, the real minimum wage remained stable at around $8.50.
The report says 6.7 per cent of all paid employees earned the minimum wage in 2013, up from 5.0 per cent in 1997.
It says young employees, less-educated employees, part-timers and people in service industries were most likely to be paid minimum wage
Note to readers: This is a corrected story. An earlier version incorrectly stated the reference year for wages in 1986 and 1996.