A recent study from the Pew Research Center has found that the middle class in the United States is now, slightly, outnumbered by the upper and lower income strata. Pew states that "in early 2015, 120.8 million adults were in middle-income households, compared with 121.3 million in lower- and upper-income households combined." While this may not seem like a big deal at first, it is a stark difference from the 1971 data, which reported 80 million middle income households versus a combined 51.6 million households in upper- and lower-income households. 

The study, which is based on data from the Census Bureau and the Federal Reserve, defines middle income as someone who makes $24,173 for a single person, $34,186 for a married couple, $41,869 for a couple with one child, $48,347 for a couple with two, and $54,053 for a family with three. 

"In at least one sense, the shift represents economic progress: While the share of U.S. adults living in both upper- and lower-income households rose alongside the declining share in the middle from 1971 to 2015, the share in the upper-income tier grew more.Over the same period, however, the nation’s aggregate household income has substantially shifted from middle-income to upper-income households, driven by the growing size of the upper-income tier and more rapid gains in income at the top. Fully 49% of U.S. aggregate income went to upper-income households in 2014, up from 29% in 1970. The share accruing to middle-income households was 43% in 2014, down substantially from 62% in 1970.^"