If you do the comparisons in normalized dollars and compare to productivity, minimum wage (if it tracked to the same purchasing power as it did in the 1950s) would be somewhere around $26 in today's dollars. If you do the same but track to inflation, it would be about $22.
When the wage doesn't keep track to inflation, it's not 'increasing', it's a pay cut. When it doesn't track to productivity, it's a pay cut out of labor's part of any growth.
When workers earning suppressed wages compete to buy things like housing, they're bidding against the class of people that received the share of productivity they didn't- and when the folks making more bid up prices of those things, it's a double-whammy of foregone wage + increased cost-of-living.
These sources disagree among themselves if the right number is $21.45 or $26 or $20, they seem to base their analysis on productivity or inflation
Yeah, these numbers sound like a lot in some places, but those places where it 'sounds like a lot' tend to be really fucking poorer than necessary. It would hurt them not at all to have the minimum keep up with where it was in 1968 instead of being the output of both major parties in congress agreeing to fuck the working poor