Time flies when you're moving backward. With the federal minimum wage stuck at $7.25 an hour since July 24, 2009, workers now have less buying power than they did in 1997 at the start of the longest period in history without a raise.

It took 10 years, from 1997 until 2007, to raise the minimum wage above $5.15. A worker would need $7.36 today to match the buying power of the $5.15 minimum wage in 1997.

If you picture raising minimum wage as climbing a mountain, workers have fallen below the spot reached 15 years ago. But it's even worse than that because 1997 was not a minimum wage high point.

You'd have to climb higher up the mountain to reach base camp for 1956 when minimum wage was worth $8.44 in today's dollars.

You'd have to climb much higher to get to the peak reached in 1968, when the minimum wage was $10.55, adjusted for inflation.