Twenty years ago I was a very broke college student. One semester I was homeless, sleeping in university stairwells, my car, and friends' sofas. Today I have two new-bought cars (one given to my daughter in college), a colonial suburban house, and an income that is about 1,400% greater (not adjusted for inflation) than my early undergraduate years. Twenty years ago government statistics placed me in the bottom 20%; now they place me somewhere in the upper 30% or so in terms of income. But according to the study discussed in this commentary, incomes of "the lowest 20%" only increased in this time by about 20% (adjusted for inflation). Did my metioric rise help elevate that figure? No; the statistics for "the lowest 20%" only counted my income for the time that I belonged to that catagory. Once my income increased past the "lowest 20%" threshhold, I stopped contributing to the figures for that catagory.
So what do these figures truly mean? That -- adjusted for inflation -- people living in the USA's lower 20% income level today are doing better than when I resided in there.